BUILDING  STONES  AND  CLAYS 


BUILDING  STONES  AND 
CLAYS 


A  HANDBOOK  FOR  ARCHITECTS 
AND  ENGINEERS 


BY 


CHARLES  H.  RICHARDSON,  PH.  D. 


PROFESSOR  OF  MINERALOGY,  SYRACUSE  UNIVERSITY 

FIELD  GEOLOGIST  OF  THE  VERMONT  GEOLOGICAL  SURVEY 

FELLOW  OF  THE  GEOLOGICAL  SOCIETY  OF  AMERICA 

MEMBER  OF  THE  AMERICAN  CHEMICAL  SOCIETY 
AUTHOR  OF  A  COLLEGE  TEXTBOOK,  ECONOMIC  GEOLOGY,  ETC. 


With  303  Copper  Halftones  and  10  Zinc  Etchings 


PUBLISHED  BY  THE  AUTHOR 


DISTRIBUTED  BY 

THE  SYRACUSE  UNIVERSITY  BOOK  STORE 

303  UNIVERSITY  PLACE,  SYRACUSE,  N.  Y. 
1917 


COPYRIGHT,  1917, 

BY 
CHARLES  H.  RICHARDSON,  PH.  D. 


ORANGE   PUBLISHING   CO.,    SYRACUSE,    N.  Y. 


TO  MY  FATHER  AND  MOTHER 

NOW  IN  THE   EIGHTY-FIFTH  YEAR 

OF  THEIR  AGE,  INTERESTED  IN 

SCIENCE.  LITERATURE  AND  PHILOSOPHY, 

THIS  BOOK  IS  AFFECTIONATELY 


370065 


PREFACE 

The  present  volume  is  an  outgrowth  of  the  author's  needs 
in  his  own  classroom.  The  matter  is  essentially  that  pre- 
sented to  his  classes  in  a  brief  course  in  the  College  of  Applied 
Science  for  Civil  Engineers,  in  the  College  of  Fine  Arts  for 
Architects  and  in  the  College  of  Liberal  Arts  for  students  of 
Economic  Geology.  The  work  has  been  multigraphed,  bound 
and  used  as  a  manuscript  textbook.  It  is  now  published  for 
the  greater  advantage  to  his  own  students,  and  with  the  hope 
that  it  may  be  useful  to  others. 

The  object  has  been  to  furnish  an  elementary  knowledge  of 
the  essential  minerals  in  building  stones  and  the  objectionable 
minerals  they  sometimes  contain ;  to  show  the  chief  character- 
istics of  the  more  important  building  stones;  to  give  their 
geographical  distribution  and  range  in  compressive  strength ; 
to  impart  some  information  as  to  the  physical  and  chemical 
properties  of  clays  and  the  products  that  may  be  manufactured 
from  them. 

The  author  has  attempted  to  state  the  essential  facts  and 
explanations  as  clearly  and  simply  as  possible  and  to  observe 
a  logical  order  and  a  due  proportion  between  different  parts. 
The  larger  amount  of  space  is  given  to  each  type  of  building 
stone  in  the  state  where  it  is  the  most  abundant. 

Great  care  has  been  taken  in  classifying  and  arranging  the 
subject  matter  that  it  may  follow  the  order  as  closely  as 
possible  of  the  various  lecture  courses  on  building  stones  and 
clays  in  our  different  colleges  and  universities. 

The  author  wishes  to  express  here  his  great  indebtedness 
for  constant  assistance  in  the  preparation  of  this  work  to  his 
colleagues  on  the  University  Faculty :  Professors  T.  C. 
Hopkins,  Burnett  Smith,  A.  E.  Brainerd,  B.  W.  Clark  and 
H.  G.  Turner.  Also  his  greater  indebtedness  to  Prof.  G.  H. 
Chadwick  of  the  University  of  Rochester  for  his  careful 
checking  of  results  and  verifying  data,  and  to  Prof.  W.  F. 
Prouty  of  the  University  of  Alabama  for  his  contribution  on 
the  Marbles  of  Alabama. 

The  most  of  the  illustrations  are  made  from  the  author's 
own  photographs  but  he  wishes  to  recognize  the  hearty 
co-operation  of  the  United  States  Geological  Survey;  the 
Woodbury  Granite  Company,  Hardwick,  Vermont;  the 
Vermont  Marble  Company,  Proctor,  Vermont;  the  National 

vii 


viii  PREFACE 

Building  Brick  Association,  Indianapolis,  Indiana ;  the 
National  Paving  Brick  Manufacturers  Association,  Cleveland, 
Ohio;  the  Kimball  Photographic  Company,  Concord,  New 
Hampshire  and  the  I.  U.  Doust  Photographic  Company, 
Syracuse,  New  York.  Acknowledgments  for  all  other  cuts 
or  photos  are  made  under  the  respective  illustrations. 

Charles  Henry  Richardson. 

Syracuse  University,  Syracuse,  N.  Y. 
January,  1917. 


TABLE  OF  CONTENTS 

CHAPTER  I 

PAGES 
INTRODUCTION 1-14 

Definition  of  building  stones,  1.  Minerals  of  building 
stones,  1-3.  Definition,  1.  Number,  2.  Classification,  2. 
Essential,  2.  Non-essential,  3.  Description  of  minerals, 
3-14.  Quartz,  3.  The  feldspars,  3.  The  micas,  5.  The 
amphiboles,  6.  The  pyroxenes,  7.  The  nephelite  group,  8. 
The  chrysolite  group,  8.  The  epidote  group,  8.  The 
hydrous  silicates,  9.  The  carbonates,  10.  The  non-essential 
minerals,  12. 

CHAPTER  II 

PHYSICAL  PROPERTIES  AND  WEATHERING  OF  BUILDING  STONES  .  15-37 
Physical  properties,  15.  Color,  15.  Hardness,  17.  Specific 
gravity,  18.  Density,  18.  Texture,  20.  State  of  aggrega- 
tion, 21.  Chemical  properties,  21.  Structures  that  aid  in 
quarrying,  22.  Rift  and  grain,  27.  Compression,  29. 
Transverse  strength,  29.  The  weathering  of  building 
stones,  29-35.  Chemical,  29.  Vegetation,  32.  Bacteria,  32. 
Physical  agencies,  32.  Frost,  33.  Friction,  33.  '  Indura- 
tion, 33.  Life,  33.  Selection  of  building  stone,  34.  Methods 
of  testing  building  stone,  35-37.  Color  test,  35.  Corrosion 
test,  35.  Abrasion  test,  35.  Absorption  test,  36.  Freezing 
test,  36.  Expansion  and  contraction  test,  36.  Fire  resist- 
ing test,  36.  Compression  test,  37.  Elasticity  test,  37. 
Shearing  test,  37.  Specific  gravity  test,  37. 

CHAPTER  III' 

GRANITES      .      ....      .      .      .    :. 38-133 

Definition,  38.  Origin,  38.  Mode  of  occurrence,  39.  Name, 
39.  Economic  classification,  39.  Geographical  distribution, 
42.  American  granites,  42-96.  California,  42.  Colorado, 
42.  Connecticut,  45.  Delaware.  47.  Georgia,  47.  Maine,  48- 
55.  Cumberland  County,  49.  Franklin  County,  50.  Hancock 
County,  50.  Kennebec  County,  52.  Knox  County,  52.  Lin- 
coln County,  53.  Oxford  County,  53.  Penobscot  County,  53. 
Washington  County,  54.  York  County,  55.  Maryland,  55. 

ix 


TABLE    OF    CONTENTS 

PAGES 

Massachusetts,  56.  Minnesota,  60.  Missouri,  61.  Mon- 
tana, 61.  New  Hampshire,  61.  New  Jersey,  68.  New 
York,  69.  North  Carolina,  70.  Oklahoma,  71.  Pennsyl- 
vania, 71.  Rhode  Island,  71.  South  Carolina,  73.  Tennes- 
see, 73.  Texas,  73.  Utah,  74.  Vermont,  74-94.  Caledonia 
County,  75  Essex  County,  78.  Orange  County,  78.  Orleans 
County,  79.  Washington  County,  84.  Windham  County, 
90.  Windsor  County,  90.  Virginia,  94.  Wisconsin,  95. 
Wyoming,  96.  Foreign  granites,  96-100.  British  Columbia, 
96.  New  Brunswick,  96.  Nova  Scotia,  96.  Ontario,  96. 
Quebec,  96.  England,  97.  Ireland,  98,  Scotland,  98.  Egypt, 
98.  Sweden,  100.  Industrial  facts  about  granite,  100-116. 
Uses,  100.  Quarrying,  112.  Polishing,  114.  Compression 
tests,  116.  Chemical  analyses,  117.  Rocks  related  to 
granite,  120-130.  Aplite,  120.  Monzonite,  120.  Syenite,  121. 
Porphyry,  121.  Liparite,  126.  Rhyolite,  126.  Trachyte, 

126.  Phonolite,  126.     Andesite,  126.     Diabase,  127.     Basalt, 

127.  Diorite,  128.     Gabbro,  128.     Norite,  129.     Gneiss,  129. 
Volcanic  tuff,  130.    Table  showing  specific  gravity,  etc.,  131. 
References,  132. 


CHAPTER  IV 

LIMESTONES,   DOLOMITES   AND   MAKIJLES 134-228 

Definition,  134.  Impurities,  135.  Texture,  135.  Varieties, 
135.  Origin,  137.  Marbleization,  140.  Alteration,  141. 
Dolomite,  142.  Dolomite  tests,  143.  Color,  143.  Hardness, 
144.  Specific  Gravity,  144.  Distribution,  144.  Age,  144. 
American  limestones  and  marbles,  144-195.  Alabama,  144- 
152.  Arizona,  152.  Arkansas,  152.  California,  153-155. 
Colorado,  155.  Connecticut,  156.  Delaware,  157.  Florida, 
158.  Georgia,  158,  Idaho,  159.  Iowa,  159.  Illinois,  161. 
Indiana,  162.  Kentucky,  162.  Maryland,  162.  Massachu- 
setts, 162.  Minnesota,  163.  Missouri,  163.  Montana,  164. 
Nevada,  164.  New  Jersey,  164.  New  York,  165-168.  The 
Hudson  River  belt,  165.  The  Champlain  belt,  165.  The 
St.  Lawrence  Valley  belt,  167.  The  Central  belt,  167. 
North  Carolina,  168.  Ohio,  168.  Pennsylvania,  168.  Ten- 
nessee, 169.  Vermont,  170-194.  Distribution,  170.  The 
Rutland  belt,  171.  Varieties,  177-185.  The  Winooski  dis- 
trict, 185-189.  The  Plymouth  belt,  189.  Isle  La  Motte  belt, 
190.  The  Washington  district,  191-193.  The  Roxbury 
district,  193.  Virginia,  194.  Foreign  limestones  and 
marbles,  196-211.  Africa,  196.  Austria,  196,  Belgium,  196. 
Bermuda,  197.  British  Columbia,  197.  England,  197. 
Fluorite,  198.  France,  198.  Germany,  199.  Ireland,  200. 


TABLE    OF    CONTENTS  xi 

PAGES 
Italy,  200.     Greece,  210.     Mexico,  210.     Nova  Scotia,  210. 

Ontario,  210.  Quebec,  211.  Industrial  facts  about  lime- 
stones and  marbles,  211-224.  Quarrying,  211.  Manufacture, 
212.  Dressing,  212-221.  Uses,  221.  Compression  tests,  221. 
Anaylses,  222-224.  Table  showing  specific  gravity,  etc.,  225. 
References,  226. 

CHAPTER  V 

SANDSTONES 229-267 

Definition,  229.  Chemical  composition,  229.  Impurities, 
229.  Texture,  229.  Color,  229.  Varieties,  231.  Cements, 
232.  Origin,  235.  Age,  235.  American  sandstones,  235-254. 
Alabama,  235.  Arizona,  235.  Arkansas,  235.  California, 
236.  Colorado,  236.  Connecticut,  237.  Georgia,  238.  Idaho, 

238.  Illinois,    238.      Indiana,    238.      Iowa,    239.      Kansas, 

239.  Kentucky,  239.     Maine,  239.     Maryland,  239.     Massa- 
chusetts, 240.    Michigan,  241.    Minnesota,  242.    Mississippi, 
242.       Missouri,     243.       Montana,     243.       Nebraska,     243. 
Nevada,  243.     New  Jersey,  244.     New  Mexico,  244.     New 
York,  244-249.   North  Carolina,  249.    Ohio,  249-.    Oregon,  250. 
Pennsylvania,   250.     North   Dakota,   251.     Tennessee,   251. 
Texas,  253.     Utah,  253.     Virginia,  253.     Washington,  254. 
West  Virginia,  254.     Wisconsin,  254.     Foreign  sandstones, 
254-260.      Austria-Hungary,   254.      Belgium,    255.      British 
Columbia,  255.     England,  255.     France,  255.     Ireland,  255. 
Germany,   256.     India,  256.     New   Brunswick,   256.     Nova 
Scotia,   257.     Ontario,    257.      Quebec,    257.      Scotland,    257. 
South    Africa,    259.     Industrial    facts    about    sandstones, 
260-264.     Quarrying,   260.     Uses,   262.     Compression  tests, 
262.     Analyses,  263.     Table  showing  specific  gravity,  etc., 
265.     References,  266. 


CHAPTER  VI 

SHALE  AND  SLATE 267-302 

Shale,  267.  Definition,  267.  Varieties,  267.  Cements,  267. 
Uses,  268.  Analyses,  268.  Slate,  268.  Definition,  268. 
Origin,  269.  Igneous  origin,  269.  Composition,  270. 
Mineralogical  composition,  270.  Minerals  of  slates,  270. 
Classification,  270.  Impurities,  271.  Color,  271.  Import- 
ance of  color,  272.  Structure,  272.  Cleavage,  272.  Tex- 
ture, 273.  Specific  gravity,  273.  Transverse  strength,  273. 
American  slates,  273-291.  Arizona,  273.  Arkansas,  273. 
California,  273.  Georgia,  274.  Maine,  274-276.  Maryland, 
276.  Massachusetts,  276.  Michigan,  276.  Minnesota,  276. 


xii  TABLE    OF    CONTENTS 

PAGES 

New  Hampshire,  277.  New  Jersey,  277.  New  York,  277. 
Pennsylvania,  277-281.  Tennessee,  281.  Utah,  281.  Ver- 
mont, 281-289.  The  Connecticut  River  slates,  281.  The 
Memphramagog  slates,  282.  The  Cambro-Ordovician  belt, 
285-289.  Characteristics  of  western  Vermont  slates,  287. 
The  Benson  belt,  289.  Virginia,  289.  West  Virginia,  290. 
Foreign  slates,  291-292.  Canada,  291.  England,  291. 
France,  292.  Wales,  292.  Industrial  facts  about  slates, 
292-300.  Quarrying,  292.  Manufacture,  293.  Measure- 
ment, 295.  Uses,  295.  Slate  waste,  296.  Comparative 
tests,  297.  Chemical  analyses,  297.  References,  301. 

CHAPTER  VII 

SERPENTINE  AND  STEATITE 303-322 

Serpentine,  303.  Origin,  304.  Characteristics,  304.  Ameri- 
can serpentines,  304--309.  California,  304.  Connecticut, 
305.  Georgia,  305.  Maine,  305.  Maryland,  305.  Massa- 
chusetts, 306.  New  Jersey,  306.  New  York,  306. 
North  Carolina,  306.  Pennsylvania,  306.  Vermont,  306. 
Washington,  309.  Foreign  serpentines,  309-311.  Canada, 
309.  England,  309.  Ireland,  310.  Italy,  310.  Industrial 
facts  about  serpentine,  311.  Compression  tests,  312. 
Chemical  analyses.  312.  References,  313.  Steatite,  314. 
Composition,  314.  Origin,  314.  Characteristics,  315. 
American  steatites,  315-319.  Arkansas,  315.  California, 

315.  Maine,    316.      Maryland,    316.      Massachusetts,    316. 
New    Hampshire,    316.     New   York,    316.      North   Carolina, 

316.  Pennsylvania,  316.     South  Carolina,  316.     Texas,  316. 
Vermont,  317.  Virginia,  317.   Industrial  facts  about  steatite, 
319-321.     Uses,  319.     References,  322. 

CHAPTER  VIII 

CLAYS 323-335 

Clays,  323.  Definition,  323.  Mineralogical  composition, 
323.  Chemical  composition,  323.  Size  of  grains,  323. 
Origin,  324.  Residual  clays,  325.  Sedimentary  clays, 
325.  Glacial  clays,  325.  Eolian  clays,  325.  Geological 
horizon,  326.  Physical  properties,  326.  Plasticity,  326. 
Fusibility,  327.  Color,  327.  Slaking,  327.  Tensile  strength, 
327.  Air  shrinkage,  328.  Fire  shrinkage,  328.  Chemical 
components,  329.  Kaolinite,  329.  Silica,  329.  Alumina, 
329.  Iron,  330.  Lime,  331.  Magnesia,  331.  Alkalies, 
331.  Titanium  dioxide,  332.  Manganese  oxide,  332.  Sul- 
phuric acid,  332.  Water,  332.  Organic  matter,  333. 
Chemical  analysis,  333. 


TABLE    OF    CONTENTS  xiii 

CHAPTER  IX 

PAGES 

MINING  AND  WASHING  CLAYS     ....',. 336-344 

Mining,  336.  Quarrying,  336.  Wheel  scraper,  336.  Steam 
shovel,  336.  Open  pit,  336.  Undermining,  338.  Under- 
ground mining,  338.  Drifting,  339.  Shaft,  339.  Haulage, 

339.  Preparation  of  clay,  340.     Crushing,  340.     Screening, 

340.  Washing,  '340.      Cyclonic  separation,    342.     Employ- 
ment of  clays,  342.   Value,  342.   Uses,  342.   References,  344. 

CHAPTER  X 

BUILDING  BRICK .      »     .      .      .      .      .      .      .   345-360 

Building  brick,  345.  Pressed  brick,  345.  Enamel  brick, 
345.  Fire  brick,  345.  Molding,  347.  Burning,  347.  Water 
smoking,  348.  Dehydration  and  oxidation,  348.  Vitrifica- 
tion, 349.  Coloration,  350.  Artificial  brick  colors,  350. 
Classification  of  building  brick,  351.  Classification  accord- 
ing to  method  of  molding,  351,  Classification  according 
to  position  in  kiln,  352.  Classification  according  to  use, 
353.  Tests  for  building  brick,  354.  Brick  building  in  1914, 
356.  Brick  and  tile  production  in  1915,  357.  References, 
360. 

CHAPTER  XI 

PAVING   MATERIALS      ...      .      .      .      .      .      .      .      .     .      .      .   361-382 

Paving  brick,  361.  History,  361.  Definition,  361.  The 
clay,  361.  Manufacture,  362.  Molding,  363.  Re-pressing, 
363.  Drying,  364.  Burning,  364.  Size,  365.  Form,  365. 
Requisites,  366.  Testing,  367.  Merits  of  brick  pavements, 
370.  •  Price  of  brick  pavements,  371.  Stone  pavements, 
373.  History,  373.  Size  of  blocks,  373.  Granite,  373.  Trap, 
375.  Sandstone,  376.  Limestone,  379.  Road  building  rocks, 

379.  Requisites,   379.     Trap,   379.     Granite,   380.     Felsite, 

380.  Limestone,  380.     Sandstone,  380.     Chert,  380.     Slate, 

381.  Shale,  381.     Field  stones,  382. 

CHAPTER  XII 

CEMENT  AND  CONCRETE     «. .'..'...      .      .   383-393 

Cement,  383.  History,  383.  Quicklime,  384.  Lime  mortar, 
385.  Hydraulic  lime,  385.  Natural  cement,  385.  Portland 
cement,  386.  White  Portland  cement,  389.  Pozzulana,  389. 
Properties  of  cement,  390.  Concrete,  392.  Advantages  of 
concrete,  392.  Theory  of  concrete,  392.  Gravel  vs.  broken- 
stone  concrete,  393.  Portland  cement  vs.  natural  cement, 
393.  Wet  vs.  dry  concrete,  393. 


xiv  TABLE    OF    CONTENTS 

CHAPTER  XIII 

PAGES 

ARTIFICIAL    STONE 394-403 

Beton-Coignet,  394.  Portland  stone,  394.  Sorel  stone,  394. 
McMurtrie  stone,  395.  Frear  stone,  395.  Ransome  stone, 
395.  Artificial  marble,  396.  Cut  cast  stone,  397.  Atlantic 
terra  cotta,  402.  References,  403. 

APPENDIX  I, — SOME  IMPORTANT  STONE   STRUCTURES      ....   404-405 

APPENDIX    II, — GLOSSARY 406-422 

INDEX  .    423-437 


BUILDING  STONES  AND  CLAYS 


CHAPTER  I 

INTRODUCTION 

The  term  building  stones  as  here  used  embraces  all  those 
forms  of  igneous,  sedimentary  and  metamorphic  rocks  that 
are  utilized  for  structural  or  decorative  purposes,  whether 
that  use  be  large  as  in  the  case  of  granites,  or  small  like  the 
ophicalcites. 

The  igneous  rocks  are  treated  first,  even  though  they  are 
more  difficult  for  the  beginner  to  understand,  because  they  are 
the  ultimate  source  of  the  sedimentaries  and  their  meta- 
morphic derivatives.  This  arrangement,  however,  does  not 
preclude  the  study  of  the  sedimentaries  first,  if  one  so  chooses. 

In  this  discussion  an  attempt  has  been  made  to  give  the 
reader  some  of  the  more  salient  geological  and  mineralogical 
features,  both  natural  and  artificial,  to  enable  the  architect 
and  engineer  by  simple  tests  to  determine  what  objectionable 
constituents,  if  any,  are  present  and  thereby  select  wisely 
material  that  will  last  well  and  be  harmonious  in  its 
environment. 

The  author  realizes  that  it  is  not  from  books  alone  that 
Geology  and  Mineralogy  are  learned.  It  requires  a  large  and 
varied  suite  of  dressed,  unpolished  and  polished  specimens, 
together  with  a  careful  study  of  their  structural  relations  in 
the  field,  to  enable  one  to  choose  only  the  best  material. 
It  is  furthermore  essential  to  see  the  stone  quarried,  dressed 
and  seasoned. 

MINERALS  OF  BUILDING  STONES 

Definition. — A  mineral  is  generally  defined  as  a  natural 
inorganic  element,  or  compound,  with  fairly  definite  chemical 
composition.  A  rock  is  a  mineral  aggregate.  This  aggrega- 
tion must  be  an  essential  portion  of  the  crust  of  the  earth. 
To  be  a  geological  formation  it  must  represent  a  mappable 
area.  The  igneous  rocks  may  occur  either  as  eruptives  that 
have  flowed  out  over  the  surface  of  older  formations,  or  as 
irruptives  in  stocks,  sheets,  dikes,  etc.,  that  appear  at  the  sur- 
face only  through  continental  denudation.  The  sedimentary 


2  ,    _    ^   ^BUILDING    STONES   AND    CLAYS 

rocks  occur  in  stratified  "beds.  In  some  instances  the  planes 
of  stratification  are  lost. 

Number. — The  number  of  minerals  necessary  in  the  forma- 
tion of  a  given  type  of  building'  stone  is  exceedingly  small. 
Calcite  is  the  only  mineral  necessary  in  statuary  marble. 
Analyzed  samples  of  this  marble  from  western  Vermont  have 
given  99.5  per  cent  calcite  and  .5  per  cent  silica.  A  sandstone 
may  consist  of  little  more  than  grains  of  quartz  held  together 
by  the  pressure  to  which  they  have  been  subjected.  A  true 
syenite  requires  but  two  minerals,  orthoclase  and  hornblende. 
A  granite  demands  the  presence  of  quartz  and  orthoclase ; 
and  usually  some  ferromagnesian  mineral  is  present,  as 
biotite  or  hornblende. 

A  microscopic  examination  of  building  stones  usually  adds 
a  few  minor  minerals  to  the  requisite  number  for  a  given  type 
of  rock.  These  are  of  importance  in  the  weathering  of  a 
stone  but  not  necessary  in  its  commercial  definition. 

Classification. — The  minerals  of  building  stones  are  classified 
as  essential  and  accessory,  or  as  original  and  secondary.  The 
essential  minerals  determine  the  definition  of  a  given  type  of 
rock.  Quartz  is  essential  in  a  sandstone,  quartz  and  ortho- 
clase in  a  granite.  An  accessory  mineral  is  one  that  is  usually 
present  but  of  minor  •  importance.  Its  presence  may  be 
recognized  microscopically  or  macroscopically.  For  example, 
apatite  or  magnetite  may  occur  in  a  granite. 

An  original  mineral  as  applied  to  the  necessary  constituents 
of  building  stones  is  one  that  was  present  when  solidification 
first  occurred.  It  is  always  an  essential  mineral,  but 
original  minerals  are  not  always  essential.  Apatite  and  zircon 
when  present  in  granites  are  amongst  the  first  minerals  to 
solidify  from  an  acid  magma  yet  they  are  not  essential  to  the 
commercial  definition  of  a  granite.  A  secondary  mineral  is 
one  that  is  derived  from  some  other  mineral  or  minerals  either 
by  the  chemical  action  of  percolating  waters  or  by  molecular 
rearrangement.  Olivine  is  an  essential  mineral  in  peridotite 
while  serpentine  results  from  the  loss  of  the  iron  and  the 
hydration  of  the  magnesium  in  olivine. 

In  order  to  best  understand  the  nature  of  structural  stones 
some  knowledge  of  mineralogy  is  necessary.  Even  a  descrip- 
tive elementary  method  of  treating  minerals  has  some  value. 
It  would  not  seem  advisable  to  enter  into  detail  to  any 
considerable  extent  for  most  minerals  may  be  recognized  by 
a  few  simple  tests.  These  will  enable  an  architect  or  engineer 
to  arrive  easily  at  his  definition  of  a  given  type  of  structural 
stone. 

Essential. — The  number  of  minerals  occurring  as  essential 
constituents  in  building  stones  is  exceedingly  small.  The  list 


MINERALS    OF   BUILDING   STONES 

may  be  summed  up  in  the  various  varieties  of  quartz ;  four 
families,  the  feldspars,  micas,  amphiboles,  pyroxenes ;  three 
anhydrous  silicates,  olivine,  epidote,  nephelite,  or  the  variety 
eleolite ;  three  hydrous  silicates,  talc,  serpentine,  chlorite ; 
three  carbonates,  calcite,  aragonite,  dolomite  ;  and  one  sulphate, 
gypsum. 

Non-essential. — The  non-essential  minerals  are  vastly 
greater  in  number  but  they  occur  in  small  proportions  and 
often  of  microscopic  size.  The  presence  of  some  of  these  is 
exceedingly  deleterious  while  others  are  harmless.  These 
may  be  summed  up  in  two  elements,  four  sulphides,  two 
carbonates,  seven  oxides,  one  phosphate,  one  chloride,  one 
fluoride,  together  with  several  anhydrous  and  hydrous  silicates. 
A  brief  statement  concerning  the  more  important  of  these 
minerals  will  suffice. 

DESCRIPTION  OF  MINERALS 

Quartz. — Quartz  is  an  oxide  of  silicon,  SiO2.  It  is  ?  in  the 
scale  of  hardness,  2.65  in  specific  gravity,  vitreous  in  luster, 
insoluble  in  the  common  mineral  acids.  It  can  easily  be 
recognized  by  its  insolubility,  its  luster  and  superior  hardness 
to  all  other  essential  minerals  in  building  stones.  It  is  one  of 
the  most  widely  distributed  of  all  minerals.  It  composes 
most  of  the  sands  of  the  sea  shore  and  river  plains.  It  is 
essential  in  all  sandstones  ,and  mica  schists.  It  is  present  in 
all  granites,  gneisses,  quartzites,  liparites,  etc.  The  quartz 
grains  in  fragmental  sandstones  have  sometimes  undergone 
a  secondary  growth  by  a  deposition  of  crystallized  silica  with 
like  orientation  to  the  original  nucleus. 

Quartz  is  furthermore  one  of  the  most  indestructible  of 
minerals  for  there  is  no  higher  oxide  of  silicon.  The  fluid 
cavities  sometimes  found  in  quartz  cause  the  rock  mass  rich 
in  silica  to  scale  after  being  subjected  to  the  heat  of  a  burning 
building. 

The  Feldspars. — The  term  feldspar  is  a  family  name  embrac- 
ing a  group  of  minerals  with  many  characteristics  in  common. 
They  are  silicates  of  aluminum  with  either  potassium,  sodium, 
or  calcium  present,  while  magnesium  and  iron  are  always 
absent.  There  are  many  intermediate  species  between  the 
sodium  and  calcium  members  which  are  connected  with  each 
other  by  insensible  gradations.  Some  of  the  common  charac- 
teristics of  the  family  are  as  follows:  (1)  Crystallization  in 
the  monoclinic  or  triclinic  systems  with  a  close  resemblance 
among  the  different  species  in  general  habit,  cleavage  angle 
and  method  of  twinning.  (2)  Colors  shading  from  white  to 
green  or  red.  (3)  Hardness  falling  between  6  and  6.5.  (4) 
Specific  gravity  generally  between  2.5  and  2.75. 


4  BUILDING    STONES    AND    CLAYS 

Orthoclase,  K2O,  A12O.,,  (>SiO.,,  is  an  acid  feldspar  occurring  as 
an  essential  constituent  in  all  granites,  most  gneisses  and  true 
syenites.  It  is  easily  recognized  by  a  possible  cleavage  angle 
of  90  degrees  and  the  absence  of  striations  on  all  cleavage 
planes.  It  fuses  at  5  and  is  insoluble  in  mineral  acids. 

Microclinc  crystallizes  in  the  triclinic  system.  Its  chemical 
composition  is  the  same  as  that  of  orthoclase,  K,O,  A1,O3, 
<"SiO2.  It  often  shows  a  peculiar  shade  of  green  which  aids 
in  distinguishing  the  crystals  from  those  of  the  other  feldspars. 
In  case  of  the  building  stones  it  often  requires  a  microscopic 
examination  to  establish  the  difference.  Its  home  is  with  the 
acid  irruptives. 

Plagioclase  is  the  term  often  given  to  designate  the  remain- 
ing members  of  the  feldspar  family  all  of  which  are  triclinic 
in  system  of  crystallization.  They  are  albite,  oligoclase.  an- 
desine,  labradorite  and  anorthite. 

Albite,  as  the  name  implies,  is  usually  white  in  color.  Its 
formula  is  Na2O,  A12O:>>,  (>Si()2.  It  fuses  at  -1  and  is  insoluble, 
in  mineral  acids.  It  occurs  in  many  granites  along  with 
orthoclase  and  is  usually  distinguishable  by  its  greater  white- 
ness. In  some  highly  colored  granites  the  few  white  crystals 
present  are  albite.  When  it  occurs  as  the  essential  feldspar 
with  hornblende  it  constitutes  a  diorite. 

Oligoclase  is  intermediate  in  composition  between  albite 
and  anorthite.  It  fuses  at  :>.«5  to  an  enamel-like  glass  and  is 
imperfectly  acted  upon  by  mineral  acids.  It  is  often  recog- 
nized by  fine  striations  or  parallel  lines  on  some  cleavage 
plane.  Its  home  is  with  both  the  irruptives  and  the  eruptives. 

Audcsinc  is  also  intermediate  between  albite  and  anorthite. 
It  fuses  in  thin  splinters  before  the  blowpipe  and  is  imper- 
fectly soluble  in  mineral  acids.  Its  color  is  usually  white 
or  gray.  It  gives  definition  to  the  rock  called  andesite.  It 
occurs  in  some  syenites  and  porphyries. 

Labradorite  is  more  basic  than  the  preceding  feldspar.  It 
fuses  at  •')  to  a  colorless  glass  and  is  partially  soluble  in  HC1. 
It  shades  in  color  from  gray  to  green  and  often  presents  a 
beautiful  iridescence,  especially  when  polished,  in  which 
blue  and  green  are  predominant  colors  but  yellow  and  fire- 
red  colors  also  occur.  It  is  often  finely  striated  upon  the 
cleavage  planes.  It  occurs  with  hypersthene  in  the  building- 
stone  known  as  norite.  Its  home  is  also  with  the  gabbros, 
diabases  and  dolerites. 

Anorthite  is  the  most  basic  member  of  the  feldspar  family. 
Its  formula  is  CaO,  A12O,,  2SiO,.  It  fuses  at  5  to  a  colorless 


MINERALS    OF   BUILDING    STONES  5 

.  glass  and  is  soluble  in  HC1  with  a  separation  of  gelatinous 
silica.  In  color  it  shades  from  white  to  red.  Its  home  is 
with  the  basic  intrusives.  Some  of  the  New  England  diabases 
bearing  anorthite  constitute  the  finest  road  metal. 

It  is  important  before  selecting  any  granite  for  a  massive 
structure  to  examine  carefully  microscopic  slides  of  the  stone. 
If  the  feldspar  has  already  suffered  kaolinization  the  rock 
should  be  rejected.  The  microscope  often  reveals  cavities 
and  flaws  so  filled  with  impurities  and  products  of  decompo- 
sition as  to  render  the  feldspar  quite  opaque.  Such  a  building 
stone  will  not  long  withstand  the  destructive  effects  of 
weathering  agencies. 

The  color  often  imparted  to  granites,  gneisses  and  quartz 
porphyries  is  due  to  the  color  of  the  prevailing  feldspar.  In 
the  red  granites  the  pigment  in  the  feldspar  is  ferric  iron. 
In  the  green  granites  it  has  been  attributed  to  ferrous  iron 
and  in  the  delicately  pink  granites  to  manganese. 

The  Micas. — The  mica  family  includes  a  series  of  closely 
related  minerals  characterized  by  a  highly  perfect  basal 
cleavage.  They  are  easily  separable  into  plates  varying  in 
thickness  from  one  thousandth  to  one  fifteen  hundredth  of 
an  inch  in  thickness.  They  all  fall  in  the  monoclinic  system. 

Muscovite,  chemically  considered,  is  an  orthosilicate  of 
aluminum,  potassium  and  hydrogen.  It  is  known  also  as 
the  potassium  mica  or  the  white  mica.  In  some  light  colored 
granites  it  is  practically  the  only  mica  present.  This  holds 
especially  true  of  the  white  granite  of  Bethel,  Vermont.  The 
thin  laminae  of  muscovite  are  flexible  and  spring  back  with 
considerable  force  into  normal  position  when  bent.  Its  hard- 
ness is  2.3.  Its  gravity  is  2.9.  Muscovite  is  insoluble  in 
the  mineral  acids,  and  when  it  bears  no  iron  it  possesses 
greater  powers  of  endurance  than  the  other  members  of  the 
mica  family. 

Biotite  is  also  an  orthosilicate  of  aluminum,  potassium, 
hydrogen,  magnesium  and  iron.  It  is  known  as  the  iron  mica 
and  the  black  mica.  The  presence  of  iron  favors  decompo- 
sition for  when  the  mineral  is  once  coated  with  a  thin  film 
of  the  oxide  of  iron  it  is  rapidly  disintegrated.  Biotite  is  2.8 
in  hardness  and  sometimes  reaches  a  specific  gravity  of  3. 
The  presence  of  large  quantities  of  biotite  in  a  granite  in- 
creases the  weight  per  cubic  foot,  and  decreases  the  life  of 
the  stone.  The  finely  pulverized  mineral  is  decomposed  by 
sulphuric  acid  with  a  separation  of  the  silica  in  minute  scales. 

Phlogopitc  is  closely  related  to  biotite  in  composition  but 


6  BUILDING    STONES    AND    CLAYS 

carries  less  iron.  It  is  known  as  the  magnesium  mica,  or 
amber  mica,  on  account  of  its  amber-like  reflections.  It  often 
exhibits  asterism  in  transmitted  light.  Its  hardness  is  2.7 
and  its  specific  gravity  :3.(S.  It  is  completely  decomposed  by 
sulphuric  acid  with  a  separation  of  the  silica  in  minute  scales. 
The  home  of  phlogopite  is  with  the  marbles  and  serpentines 
in  which  it  often  becomes  an  objectionable  constituent. 

Lcpidoniclanc  is  in  part  an  orthosilicate  and  in  part  a  more 
basic  compound.  It  is  chiefly  characterized  by  a  large  amount 
of  ferric  iron.  It  is  best  regarded  as  a  variety  of  biotite. 

The  presence  of  the  various  micas  in  limestones,  dolomites 
and  marbles  may  be  regarded  as  objectionable  for  they  are 


Fig.    1. — Boulder   of    orbicular    granite,    Orleans    County,    Vermont. 
Photo,  by   C.  H.  Richardson. 

difficult  to  polish  and  scale  off  easily  leaving  the  stone  pitted. 
In  such  rocks  the  micas  are  of  secondary  origin.  In  the 
granites  and  gneisses  the  micas  are  of  primary  origin.  They 
should  be  uniformly  scattered  throughout  the  stone  in  fine 
scales  for  with  their  perfect  cleavage  they  themselves  con- 
stitute an  element  of  weakness.  When  in  spherical  aggre- 
gations as  in  the  granite  of  Craftsbury,  Vermont,  they  give 
rise  to  the  orbicular  granites.  (See  Fig.  1.) 

The  Amphiboles. — The  amphibole  family  includes  a  group 


MINERALS    OF   BUILDING    STONES'  7 

of  minerals  that  crystallize  in  the  orthorhombic,  monpclinic 
and  triclinic  systems.  Those  occurring  in  building  stones 
fall  in  the  monoclinic  system  and  the  representatives  are 
tremolite,  actinolite  and  hornblende. 

Tremolite  is  a  silicate  of  calcium  and  magnesium.  Hard- 
ness of  5.5  and  specific  gravity  of  3.  It  sometimes  appears 
as  short,  stout  prisms,  and  sometimes  columnar,  or  fibrous. 
It  is  an  objectionable  constituent  as  a  secondary  mineral  in 
marbles,  for  the  stone  becomes  pitted  through  the  loss  of 
lime  and  the  falling  out  of  the  minute  crystals  of  tremolite. 
Furthermore,  the  mineral  often  changes  color  from  a  pure 
white  when  quarried  to  a  dirty  gray  upon  exposure  to  the 
atmosphere. 

Actinolite  is  closely  related  to  tremolite  in  composition 
but  has  a  little  of  the  magnesium  replaced  by  iron  which  im- 
parts a  bright  green  or  grayish  color  to  the  mineral.  Hard- 
ness of  5.5  and  gravity  of  3.1.  The  crystals  are  short,  bladed, 
columnar  and  fibrous.  Its  home  is  with  the  metamorphics. 

Hornblende  is  an  aluminous  variety  of  amphibole.  Hard- 
ness 5.5  to  6.  Specific  gravity  3.2.  Its  color  is  often  greenish 
black  to  black.  It  is  an  essential  constituent  in  certain 
granites  like  the  granite  of  Quincy,  Mass.,  gneisses,  schists 
and  diorites.  The  crystals  are  often  long  and  prismatic. 
The  mineral  may  easily  be  identified  by  its  black  color  and 
cleavage  angles  of  56  and  124  degrees.  The  cleavage  is  far 
more  pronounced  than  it  is  in  the  pyroxenes. 

The  Pyroxenes. — The  pyroxene  family  embraces  a  number 
of  species  that  fall  in  the  orthorhombic,  monoclinic  and  tri- 
clinic systems  of  crystallization.  The  metasilicates  of  calcium, 
magnesium  and  iron  are  the  most  prominent  members  of  the 
groups.  They  all  present  a  fundamental  prismatic  form  with 
an  angle  of  87  or  93  degrees  parallel  with  which  there  is  a 
pronounced  prismatic  cleavage. 

Enstatite  is  a  metasilicate  of  magnesium,  MgO,  SiO2.  Its 
hardness  is  5.5  and  specific  gravity  3.2.  In  color  it  is  often 
gray  but  when  iron  displaces  a  part  of  the  magnesium  the 
mineral  is  bronze-like  in  color.  Its  home  is  in  the  peridotites 
and  the  serpentines  derived  from  them.  In  its  hydration 
talc  is  the  metamorphic  product. 

Hypersthene,  (Fe,Mg)O,  SiO2.  Hardness  5.5.  Specific 
gravity  3.4.  In  color  the  mineral  shades  from  a  dark  brownish 
green  to  a  greenish  black.  Hypersthene  is  an  essential  con- 
stituent of  certain  so-called  granites  like  the  Keeseville,  N.  Y., 
norite.  It  is  also  found  in  some  gabbros  and  andesites.  It 


8  BUILDING    STONES    AND    CLAYS 

sometimes  produces  black  knots  in  the  norites.  These  rep- 
resent a  basic  segregation  in  the  cooling  of  the  magma  from 
which  norite  is  derived.  The  presence  of  much  hypersthene 
is  undesirable,  for  the  mineral,  on  account  of  its  iron  content, 
is  easily  decomposed  on  exposure  to  the  corrosive  agents 
of  the  atmosphere. 

A-ugite  is  for  the  most  part  a  normal  metasilicate  of  calcium, 
magnesium  and  iron.  Hardness  5.5.  Specific  gravity  3.4. 
Its  color  is  usually  green  or  greenish  black  and  the  crystals 
are  short,  thick  and  prismatic.  Its  cleavage  angles  of  approxi- 
mately 87  and  93  degrees,  together  with  its  grayish  green 
color,  readily  distinguish  it  from  hornblende.  It  occurs 
sparingly  in  some  building  stones  like  the  nordmarkite  of 
Mount  Ascutney,  Vermont.  It  is  an  essential  constituent 
with  the  triclinic  feldspars  in  diabase  and  basalt.  By  a  con- 
version of  the  augite  into  hornblende  the  latter  rocks  pass 
into  the  diorites. 

The  Nephelite  Group. — The  only  member  of  the  nepheline 
group  of  minerals  occurring  as  an  essential  constituent  in 
building  stones  is  nephelite.  It  is  an  orthosilicate  of  alum- 
inum, sodium  and  potassium.  Its  hardness  is  5.8.  Its  specific 
gravity  is  2.G5.  Its  home  is  with  the  intermediate  and  basic- 
rocks  rather  than  with  the  acidic.  The  syenites  bearing  the 
variety  of  nephelite  known  as  eleolite  often  present  a  greasy 
appearance  suggestive  of  an  oiled  surface.  Free  quartz  is 
absent,  for  if  an  excess  of  silica  sufficient  to  form  quartz  had 
been  present  in  the  magma  then  the  acid  feldspars  would 
have  been  formed  instead  of  nephelite.  Its  presence  in  a 
building  stone  is  easily  established  by  pulverizing  a  few 
grams  of  the  rock  and  digesting  it  with  concentrated  HC1  or 
dilute  HNO.,  when,  in  the  presence  of  nephelite,  the  silica 
of  this  mineral  will  separate  out  as  a  gelatinous  product  of 
decomposition. 

The  Chrysolite  Group. — The  one  important  member  of  this 
group  is  the  orthosilicate  of  magnesium  and  iron,  olivine, 
in  which  the  ratio  of  the  magnesium  to  the  iron  varies  widely. 
Some  analyzed  samples  have  shown  this  ratio  as  1(5  :  1,  others 
as  2  :  1.  Its  hardness  is  G.7.  Its  specific  gravity  is  3.3.  The 
mineral  is  named  from  its  olive  green  color.  Its  home  is  with 
the  basic  and  ultra-basic  rocks.  In  its  metamorphism  it 
passes  into  serpentine  which  sometimes  becomes  a  highly 
decorative  structural  stone  yet  better  suited  for  interior 
decorative  work. 

The   Epidote   Group. — The   one   important   member  of  this 


MINERALS    OF    BUILDING    STONES  9 

group  of  minerals  is  epidote  itself.  Its  hardness  is  6.8.  Its 
specific  gravity  is  3.3.  It  is  an  orthosilicate  of  calcium,  alum- 
inum and  iron  with  a  little  water  of  crystallization.  It  is  of 
a  peculiar  pistachio  green  color  seldom  represented  by  other 
minerals.  It  is  sometimes  found  sparingly  in  granites  as 
at  Enfield,  N.  H.,  and  is  a  common  constituent  of  many 
gneisses,  schists  and  serpentines. 

The  Hydrous  Silicates. — The  three  hydrous  silicates  of  con- 
siderable significance  in  structural  and  decorative  stones  are 
chlorite,  serpentine  and  talc. 

Chlorite. — The  term  chlorite  embraces  a  considerable 
number  of  minerals  closely  related  to  the  micas  but  differing 
from  them  in  brittleness  and  in  a  larger  percentage  of  water. 
Chemically  considered  the  chlorites  are  silicates  of  aluminum, 
iron  and  magnesium,  with  chemically  combined  wrater.  They 
are  characterized  by  their  green  color,  perfect  cleavage  and 
inelastic  foliae.  Their  hardness  varies  but  approximates  to  2.5 
and  their  specific  gravity  falls  between  2.5  and  2.9.  Chlorites 
are  secondary  minerals  derived  from  the  alteration  of  amphi- 
boles,  pyroxenes  and  micas. 

The  mineral  imparts  a  green  color  to  the  chlorite  schists 
which  often  consist  of  scales  of  chlorite  and  grains  of  sand. 
Chlorite  is  the  ferromagnesian  mineral  in  certain  gneissoid 
granites  like  that  of  Lebanon,  N.  H.,  which  was  first  classi- 
fied as  a  protogene  gneiss.  The  chlorite  is  here  derived  from 
the  metamorphism  of  biotite. 

Serpentine  is  a  hydrous  silicate  of  magnesium,  3MgO,2SiO2, 
2H2O.  Hardness  varying  from  2  to  4.  Its  specific  gravity 
is  2.65.  It  occurs  in  varying  shades  of  green,  sometimes 
greenish  black.  It  crystallizes  in  the  monoclinic  system  but  it 
is  the  massive  form  that  finds  use  as  a  decorative  stone. 
When  it  occurs  with  calcite,  magnesite  and  dolomite  it  con- 
stitutes the  verd  antique  marbles.  It  sometimes  occurs  as 
minute  green  patches  scattered  through  other  marbles  where 
its  presence  is  objectionable.  It  occurs  also  as  a  metamorphic 
product  resulting  from  the  alteration  of  the  magnesium  sili- 
cates in  diabase,  basalt  and  peridotite.  Massive  serpentine  is 
easily  recognized  by  its  inferior  hardness  to  marble,  its  green 
color,  its  absence  of  cleavage  'planes  and  the  large  percentage 
•of  water  derived  upon  ignition.  (See  Fig.  2.) 

Talc  is  an  acid  metasilicate,  3MgO,  4SiO2,  H2O.  Its  hard- 
ness varies  from  1  to  2.5.  Its  specific  gravity  is  2.75.  Its 
color  shades  from  white  to  green.  When  it  occurs  in  the 
massive  form  it  constitutes  the  useful  stone  known  as  steatite, 


10 


BUILDING    STONES    AND    CLAYS 


which  finds  application  in  laboratory  tables,  sinks,  stationary 
washtubs,  stoves,  etc.  The  mineral  is  easily  recognized  by 
its  soapy  feel  and  the  ease  with  which  it  can  be  abraded  with 
the  thumb  nail. 

The  Carbonates. — Calcite,  aragonite  and  dolomite  are  the 
three  carbonates  that  occur  as  essential  minerals  in  building 
stones.  They  are  easily  distinguished  from  the  preceding 
minerals  by  their  effervescence  in  HC1.  They  are  secondary 
in  origin  resulting  largely  from  the  alteration  of  other  min- 
erals, together  with  the  solution  and  fine  comminution  of  the 
testa  of  mollusks  and  crustaceans. 


/ 


Fig.  2. — Block  of  verd  antique  marble,  Roxbury,  Vermont.  Photo, 
by  C.  H.  Richardson. 

Calcite  occurs  filling  the  minute  cavities  in  the  rocks  of 
all  classes  and  of  all  ages.  Formula,  CaCO3.  Its  specific 
gravity  is  2.71.  Pure  statuary  marble  contains  little  else 
than  calcium  carbonate.  It  furnishes  the  essential  constituent 
in  most  marbles,  and  is  one  of  the  two  requisite  constituents 
of  dolomites.  Calcite  is  easily  recognized  by  its  definite 
hardness  of  3,  by  its  facile  cleavage  and  consequent  brittle- 
ness  and  by  its  rapid  effervescence  with  cold  dilute  HC1. 

Aragonite  has  the  same  formula  as  calcite  but  instead  of 
crystallizing  in  rhombohedrons  of  varied  habit  like  calcite 
it  falls  in  the  orthorhombic  system  in  prismatic  forms.  Its 


MINERALS    OP   BUILDING    STONES 


11 


hardness  is  3.7  and  its  specific  gravity  2.95.  Some  decorative 
marbles  like  the  onyx  of  San  Luis  Obispo,  California,  are 
nearly  pure  aragonite.  The  mineral  is  distinguished  from  all 
others  save  calcite  by  rapid  effervescence  in  cold  dilute  HC1, 
and  from  calcite  by  falling  to  pieces  before  the  blowpipe 
and  by  turning  a  beautiful  pink  when  the  fine  powder  is 
boiled  with  the  nitrate  of  cobalt. 

Dolomite  is  a  double  carbonate  of  calcium  and  magnesium, 
CaCO3,  MgCO3.  Its  hardness  is  3.7  and  its  specific  gravity 
2.85.  It  crystallizes  in  the  hexagonal  system  in  rhombo- 
hedrons  with  curved  faces,  often  with  a  pearly  luster.  It 
effervesces  slowly,  if  at  all,  in  cold  dilute  HC1  but  rapidly  in 
warm  HC1.  Many  of  the  white  marbles  like  that  of  Stock- 
bridge,  Mass.,  and  the  mottled  marbles  like  those  of  Swanton, 
Vermont,  are  dolomites.  (See  Figs.  3  and  4.) 


Fig.  3.  —  Polished  sample  of  jasper  marble,  Swanton,  Vermont. 
Photo,  by  C.  H.  Richardson. 

Gypsum,  CaSO4,  2H2O,  is  the  only  sulphate  that  occurs 
as  an  essential  constituent  of  any  building  stone.  Its  hard- 
ness is  2  and  its  specific  gravity  2.3.  In  color  it  is  usually 
white  but  sometimes  grayish.  It  crystallizes  in  the  mono- 
clinic  system  with  forms  simple  in  habit.  The  mineral  seldom 
occurs  in  the  crystalline  rocks  but  it  forms  extensive  beds 
amongst  the  stratified  limestones  and  clays  where  it  becomes 
a  rock  mass  of  large  commercial  significance.  Alabaster  is 
a  fine  translucent  variety  that  is  used  for  ornamental  pur- 
poses. In  the  absence  of  the  water  of  crystallization  the 
mineral  passes  into  anhydrite  which  has  been  substituted 
sometimes  for  white  marble.  This  use  is  objectionable  for 


12  BUILDING    STONES    AND    CLAYS 

anhydrite  absorbs  water  upon  exposure  and  expands  thereby 
throwing  buildings  out  of  plumb. 

The  Non-essential  Minerals. — The  number  of  non-essential 
minerals  sometimes  occurring  in  building  stones  approximates 
forty.  In  many  cases  these  are  microscopic  constituents. 
In  others  they  are  visible  to  the  eye  and  easily  recognized. 
The  lack  of  space  will  permit  an  outline  of  only  a  few  and 
these  will  be  the  ones  most  objectionable  when  present  in 
any  building  stone. 

Pyrite,  FeS2,  is  a  disulphide  of  iron.  Its  hardness  is  f>.3. 
Its  specific  gravity  is  5.  In  color  it  is  a  pale  brass  yellow. 
It  occurs  in  building  stones  in  the  form  of  cubes  of  the  iso- 


Fig.    4. — Polished    sample    of    lyonaisc    marble,    Swanton,    Vermont. 
Photo,  by  C.  H.  Richardson. 


metric  system  and  in  a  microscopic,  granular  and  amorphous 
condition.  In  this  latter  form  its  oxidation  is  far  more  active 
than  when  in  cubes.  In  its  decomposition  either  soluble 
sulphates  or  free  sulphuric  acid  is  formed  and  the  stone  soon 
presents  a  dingy  and  unkempt  appearance.  In  the  calcareous 
rocks  bearing  magnesium  the  presence  of  pyrite  becomes 
exceedingly  objectionable.  The  free  sulphuric  acid  formed 
in  the  decomposition  of  the  pyrite  unites  with  magnesium 
and  forms  a  soluble  efflorescent  salt  that  creeps  to  the  surface 
and  is  replaced  from  time  to  time  by  the  less  soluble,  yet 


MINERALS    OF   BUILDING    STONES  13 

objectionable,  calcium  sulphate.  According  to  James  Hall 
efflorescence  is  frequently  observed  on  buildings  constructed 
of  the  bluestone  of  the  Hudson  River  group.  In  case  the 
mortar  with  which  the  structural  blocks  are  laid  contains 
magnesium  efflorescent  patches  may  be  observed  creeping 
mainly  from  the  joint  planes  and  bedding  planes  of  the 
finished  structure.  Such  an  exhibition  may  be  seen  on  St. 
Peter's  Church,  State  Street,  Albany,  N.  Y. 

Marcasite  has  the  same  chemical  formula  as  pyrite,  FeS2- 
Its  hardness  is  6.3  and  its  gravity  is  4.9.  It  crystallizes  in 
prismatic  forms  in  the  orthorhombic  system  and  is  paler  in 
color  than  pyrite.  A.  Julien  has  pointed  out  the  greater 
tendency  of  marcasite  to  undergo  atmospheric  alterations  and 
shown  its  profound  influence  upon  the  durability  of  building 
stones.  Where  the  two  forms  of  iron  disulphide  occur  to- 
gether, either  through  crystallization  or  alteration,  as  the 
proportion  of  marcasite  increases  the  specific  gravity  of  the 
rock  mass  decreases,  the  color  becomes  paler,  and  the  danger 
of  objectionable  weakening  and  discoloration  is  increased. 

Owing  to  the  tendency  of  all  sulphides  to  decompose  upon 
exposure  to  the  atmosphere  structural  stones  showing  their 
presence  sho.uld  be  rejected.  Sulphur  to  the  amount  of  .2 
per  cent  may  be  readily  detected  by  fusing  the  rock  in 
powdered  form  with  sodium  carbonate  on  charcoal  with  the 
blowpipe,  transferring  the  fused  mass  to  a  silver  •  coin, 
moistening  with  water,  when  in  the  presence  of  sulphur,  a 
dark  stain  due  to  the  formation  of  silver  sulphide  will  appear 
on  the  coin. 

Siderite  is  a  carbonate  of  iron,  FeCO3.  Its  hardness  is  3.7 
and  its  specific  gravity  3.8.  Its  color  is  usually  gray  but  it 
turns  brown  upon  exposure  to  the  atmosphere.  The  mineral 
crystallizes  in  curved  rhombohedrons  of  the  hexagonal  system 
and  occurs  as  scattered  crystals  or  in  groups  in  many  clays 
and -limestones.  Any  limestone,  dolomite  or  marble,  bearing 
even  microlites  of  siderite  will  soon  present  a  dull  or  dead 
surface.  0.1  of  1  per  cent  of  this  mineral  can  be  detected 
by  the  borax  bead  which  in  its  presence  becomes  bottle  green 
in  the  reducing  flame. 

Ankcrite,  2CaCO3,  MgCO3,  FeCO3,  is  a  triple  carbonate. 
Its  hardness  is  3.7  and  its  specific  gravity  3.  It  crystallizes 
in  the  same  forms  as  siderite.  Its  occurrence  in  building 
stones  is  less  frequent  than  that  of  siderite  but  when  present 
it  is  always  objectionable. 

Hematite,    Fe2O3,    is   an   oxide   of    iron.      Its   hardness*  is    6 


14  BUILDING    STONES   AND    CLAYS 

and  its  gravity  5.  Its  color  shades  from  red  to  black  but  its 
streak  is  cherry  red  or  blood  red.  It  occurs  in  the  rocks  of 
all  ages.  The  specular  variety  is  mostly  confined  to  the 
crystalline  or  metamorphic  rocks.  In  granites  it  is  usually 
confined  to  minute  scales  of  bright  red  color.  In  an  amor- 
phous form  it  furnishes  the  cement  in  the  red  or  brownish 
sandstones.  Its  occurrence  as  a  cement  is  not  as  frequent 
as  that  of  the  hydrated  oxides  of  iron,  turgite  and  limonite. 
These  are  present  in  the  Triassic  sandstones  of  Long- 
meadow,  Mass. 

Magnetite,  Fe3O4,  is  distinguished  from  the  other  oxides 
of  iron  by  its  black  color  and  strong  magnetism.  Its  hard- 
ness is  G  and  its  specific  gravity  is  5.1.  It  crystallizes  in 
regular  octahedrons  of  the  isometrit  system.  Its  home  as 
an  original  constituent  is  in  many  granites  and  metamorphic 
sedimentaries.  It  is  almost  invariably  present  in  the  basic 
igneous  rocks.  Whenever  magnetite  is  present  in  an  appre- 
ciable quantity  in  any  rock  it  ultimately  becomes  converted 
into  the  hydrated  oxide  of  iron  which  stains  the  stone  a 
rusty  red  color. 

Garnet,  3RO,  R2O3,  3SiO2.  R  stands  for  the  bivalent  metals 
like  calcium  and  magnesium,  R2  represents  the  trivalent 
metals  like  aluminum  and  ferric  iron.  The  hardness  of  garnet 
is  7'.  Its  specific  gravity  is  3.3.  In  color  the  mineral  shades 
from  white  to  red.  It  crystallizes  in  the  isometric  system  in 
regular  dodecahedrons  and  leucitohedrons.  Its  home  is  with 
the  granites,  gneisses,  schists,  limestones,  and  sometimes 
serpentines.  Occasionally  it  appears  in  the  basic  irruptives. 
Its  presence  in  any  type  of  building  stone  is  objectionable. 
On  account  of  its  brittleness  it  breaks  away  from  its  matrix 
in  the  dressing  of  a  stone  and  renders  a  perfect  polish  far 
more  difficult  to  obtain.  Iron  garnets  break  down  due  to 
the  oxidation  of  the  iron  on  long  exposure  to  the  atmosphere 
and  the  stone  becomes  stained  with  the  characteristic  iron 
rust. 


CHAPTER  II 

PHYSICAL  PROPERTIES  AND   WEATHERING 
OF  BUILDING  STONES 

Physical  Properties. — There  are  several  physical  properties 
that  materially  affect  the  value  of  building  stones.  Some- 
times these  properties  have  greater  significance  than  the 
minerals  themselves. 

Color. — The  color  of  a  stone  is  often  a  guide  to  its  suit- 
ability for  a  definite  purpose.  A  dark  and  somber  sandstone 
would  appear  inharmonious  in  a  residential  section  in  a  large 
city  where  all  neighboring  buildings  were  constructed  of  a 
creamy  white  sandstone,  or  a  white  marble.  Many  an 
architect  has  builded  well  because  he  selected  only  those 
colors  that  were  harmonious  in  their  environment.  The  color 
of  building  stones  is  widely  varied  and  the  opportunity  of 
choice  correspondingly  large.  The  color  may  be  due  to  one 
or  more  of  several  causes.  Pink  tinted  feldspars  give  rise 
to  a  pink  granite  like  that  of  Westerly,  R.  I.  RecKorthoclase 
renders  the  prevailing  color  of  the  resulting  granite  red,  like 
that  of  Peterhead,  Scotland.  Sometimes  it  is  due  to  a  com- 
mingling of  the  feldspars  with  small  crystals  or  even  scales 
of  biotite  as  in  the  light  and  dark  granites  of  Barre,  Vermont. 
If  the  feldspars  are  clear  and  glassy  they  absorb  light,  and 
if  they  are  white  and  opaque  they  reflect  light.  (See  Figs. 
5  and  6.) 

The  chief  coloring  matter  in  red  sandstone  is  the  ferric 
oxide,  Fe2O3.  This  may  appear  as  a  pigment  in  the  individual 
sand  grains  that  comprise  the  essential  mineral  of  the  rock 
mass,  or  it  may  appear  as  the  cement  that  binds  the  sand 
grains  together.  The  hydrated  oxides  of  iron  serving  as 
cements  afford  colors  shading  from  a  reddish  brown  to  a 
yellow  hue.  Clay  as  a  cement  in  sandstones  produces  a  drab 
or  blue  coloration.  A  gray  color  may  also  be  produced  by 
the  presence  of  the  carbonates  and  sulphides  of  iron.  The 
pigment  in  the  black  marbles  of  Glens  Falls,  N.  Y.,  is  uncom- 
bined  carbon.  (See  Figs.  7  and  8.) 

The  color  of  building  stones  in  many  cases  is  not  permanent. 
The  nordmarkite  of  Mount  Ascutney,  Vermont,  turns  green 

15 


16  BUILDING    STONES    AND    CLAYS 

upon  exposure  to  the  atmosphere.  Sandstones  and  limestones 
containing  carbonaceous  matter  often  bleach.  The  red  and 
green  slates  may  fade.  If  the  minerals  responsible  for  these 


Fig.  5. — Polished  disc  of  medium  gray  granite,  Boutwell,  Milne  and 
Varnum  quarry.  Barre,  Vermont.      Photo,  by  C.   H.  Richardson. 


Fjg.   Q — Polished   slab   of   white   granite,   Bethel,   Vermont.      Photo, 
by  C.  H.  Richardson. 


PHYSICAL  PROPERTIES  AND  WEATHERING      17 

changes  in  color  are  not  uniformly  distributed  throughout  the 
stone  the  structure  becomes  blotched  and  unsightly.  (See 
Fig.  9.) 

Hardness. — The  hardness  of  a  mineral  is  its  resistance  to 
abrasion.     The    resistance    to    abrasion    in    a    building    stone 


Fig.  7. — Small  block  of  red  Medina  sandstone,   Medina,  New  York. 
Photo,  by  C.  H.  Richardson. 


Fig.  8. — Rock  faced  sample  of   Warsaw  bluestone,  Warsaw,    New 
York.     Photo,  by  C.   H.  Richardson. 


depends  upon  the  hardness  of  the  individual  grains  themselves 
and  upon  their  state  of  aggregation.  A  sandstone  whose 
individual  grains  are  7  in  the  scale  of  hardness  may  wear 
away  rapidly  from  the  solution  of  the  cement  that  binds  the 


18  BUILDING    STONES    AND    CLAYS 

sand  grains    together.     Such   stones   are   not  well   suited   for 
risers,  treads  and  thresholds. 

Specific  Gravity. — The  weight  of  a  cubic  foot  of  building 
stone  becomes  an  important  factor  where  haulage  by  teams 
demands  a  certain  price  per  hundred  weight  rather  than  per 
cubic  foot.  This  weight  may  be  ascertained  by  multiplying 
the  specific  gravity  of  the  stone  by  62.5,  the  weight  of  a  cubic 
foot  of  water.  However,  the  more  dense  a  stone  is  the  heavier 
it  will  be. 


mmm  mm 


Fjg  9 — s^b  Of  rec[  slate  from  Granville,  New  York,  showing  a 
white  vein-like  band  formed  by  the  leaching  out  of  the  pigment  in 
the  slate.  Photo,  bv  C.  H.  Richardson. 


Density. — The  density  of  a  stone  is  its  degree  of  compact- 
ness. The  more  dense  a  building  stone  is  the  less  water  it 
will  absorb,  and  consequently  it  possesses  less  danger  of 
injury  from  freezing  when  the  quarry  water  is  present  in  the 


PHYSICAL  PROPERTIES  AND  WEATHERING     19 

blocks.     Such  building  stones  also  possess  greater  compres- 
sive  and  tensile  strength. 


Fig.  10. — Agate  conglomerate,  Brazil.     Photo,  by  C.  H.  Richardson. 


j 


:w$mm 


Fig.     11. — Lambertville    trap     rock     (diabase),     Lambertville,     New 
Jersey.     By  courtesy  of  J.   Volney  Lewis. 


20  BUILDING    STONES    AND    CLAYS 

Texture. — The  texture  of  building  stones  is  widely  varied. 
It  ranges  from  a  coarsely  porphyritic  texture  in  the  pegma- 
tites, and  the  large,  rounded,  or  angular  fragments  in  the 


Fig.   12. — Anticline  in  memphremagog  slate  belt,  Albany,  Vermont. 
Photo,  by  C.   H.   Richardson. 


Fig.     13.  —  Small    anticlinorinm     from     Memphremagog    slate    belt, 
Woodbury,  Vermont.     Photo,  by  C.  H.  Richardson. 

conglomerates,  to  a  fine  microscopic  assemblage  of  minerals 
as  in  the  basalts,  or  the  slates  derived  from  the  ashes  of  extinct 
volcanoes.  The  texture  is  macroscopic  when  the  individual 
minerals  can  be  easily  ascertained  by  the  naked  eye  and 
microscopic  when  the  aid  of  a  petrographic  microscope  is 


PHYSICAL  PROPERTIES  AND  WEATHERING      21 

demanded  for  the  definition  of  a  structural  or  decorative  stone. 
(See  Figs.  10  and  11.) 

State  of  Aggregation. — The  hardness,  or  softness,  of  a  rock 
depends  quite  largely  upon  this  factor.  It  influences  also  the 
working  qualities  of  a  stone.  If  the  grains  adhere  loosely 
like  the  itacolumite  of  North  Carolina,  the  stone  is  friable. 
If  a  stone  is  exceedingly  fine  grained  and  compact  it  is  called 
flinty. 


Fig.  14. — E.  R.  Fletcher  granite  quarry,  Woodbury,  Vermont,  show- 
ing dome-like  sheeted  structure.     Photo,  by  C.  H.  Richardson. 


Chemical  Properties. — Many  building  stones  have  been 
analyzed  quantitively  and  their  percentage  composition  cal- 
culated. From  such  analyses  a  building  stone  like  granite 
which  is  rich  in  its  silica  content  is  called  acidic.  A  syenite, 
bearing  no  free  quartz,  consisting  of  orthoclase  and  some 


22  BUILDING    STONES'  AND    CLAYS 

ferromagnesian  mineral,  intermediate.  Rocks  possessing  no 
free  silica  or  orthoclase  and  therefore  low  in  their  silica 
content  are  classified  as  basic.  Rocks  consisting  principally 
of  calcium  carbonate,  or  calcium  and  magnesium  carbonates, 
are  calcareous.  Those  rich  in  clay  are  argillaceous.  When 
rich  in  carbon  they  are  carbonaceous.  When  iron  is  abundant 
they  are  called  ferruginous,  and  when  they  enclose  bitumen 
they  are  bituminous. 

Structures  that  Aid  in  Quarrying. — The  structure  in  sedi- 
mentary rocks  is  anticlinal  when  an  arch-like  fold  inclines  in 
opposite  directions  from  an  axis.  (See  Figs.  12  and  1:3.) 

The  corresponding  arrangement  of  the  sheets  in  a  sheeted 
granite  quarry  suggests  a  dome.  (See  Fig.  14.) 

The  structure  of  sedimentary  rocks  is  synclinal  when  they 
form  a  trough-like  fold  or  bend  in  the  same  direction.  (See 
Fig.  15.) 


Fig.  15. — Syncline  in  scricitc  schist,  Wolcott,  Vermont.  Photo,  by 
C.  H.  Richardson. 

Joint  planes  are  common  features  in  the  rock  of  all  classes 
and  of  all  ages.  In  the  granites  they  represent  structure 
planes  that  result  from  the  cooling  of  a  molten  mass,  and  are 


PHYSICAL  PROPERTIES  AND  WEATHERING     23 


BUILDING    STONES    AND    CLAYS 


•I 


PHYSICAL  PROPERTIES  AND  WEATHERING      25 

nearly  at  right  angles  to  the  cooling  surfaces.  In  the  marble 
deposits  a  considerable  amount  of  heat  was  involved  in  their 
calcitization.  As  the  temperature  again  falls  to  normal,  joint 
planes  are  formed.  There  is  always  a  large  diminution  in 
volume  during  the  dolomitization  of 'any  limestone.  Joint 
planes  result  also  from  compressive  or  tortional  strain.  Each 
strain  resolves  itself  into  two  components  which  produces 
two  sets  of  joints  that  intersect  at  an  angle  of  about  90°  and 
form  an  angle  of  45°  with  the  direction  of  the  strain.  W.  O. 
Crosby  recognizes  vibratory  strains  as  capable  of  producing 
joints.  (See  Fig.  16.) 

Bedding  planes  correspond  in  the  sedimentaries  to  the 
natural  divisions  that  separate  the  successive  layers  into 
blocks  of  varying  thickness.  If  these  blocks  become  too  thick 


m 


Fig.  18. — Jones  Brothers  quarry,  Barre,  Vermont,  showing  rift  and 
grain  of  the  granite  blocks.     Photo,  by  C.  H.  Richardson. 

difficulties  may  be  encountered  in  quarrying.  If  the  blocks 
are  too  thin  there  is  a  large  amount  of  waste  in  the  handling 
of  the  stone  because  their  thickness  \vill  not  meet  specified 
requirements.  In  case  a  paving  stone  only  is  desired 
extremely  thin  beds  may  be  advantageous.  In  granite  masses 
these  planes  are  parallel  with  the  quarry  floor.  When  the 


BUILDING    STONES    AND    CLAYS 


PHYSICAL  PROPERTIES  AND  WEATHERING      27 


blocks  are  comparatively  thin  the  stone  is  spoken  of  as  having 
a  sheeted  structure.  The  position  of  these  beds  exerts  a 
profound  influence  upon  the  quarrying  of  the  stone.  (See 
Fig.  17.) 

Rift  and  Grain. — Every  block  of  stone  quarried  must  have 
three  dimensions,  and  so  there  are  three  directions  along 
which  stones  split  with  more  or  less  ease.  Quarrymen 
everywhere  take  advantage  of  these  directions  in  working 
the  stone  into  uniform  blocks. 

The  most  pronounced  of  these  directions  is  usually  parallel 
with  the  direction  of  the  major  joints.  It  is  generally  called 
the  rift.  In  the  igneous  rocks  it  is  often  parallel  with  the 
quarry  floor  or  with  the  sheets  themselves  where  a  sheeted 


Fig.    20. — Drawing   to    explain    rift   and    grain. 
Richardson. 


Drawing   by   C.    H. 


structure  is  pronounced.  In  the  sedimentaries  the  rift  is 
often  parallel  with  the  planes  of  sedimentation.  (See  Figs. 
18  and  19.) 

The  grain  is  at  right  angles  to  the  rift.  The  third  direction 
is  called  the  end  grain  or  the  head  grain.  A  stone  may  work 
easily  in  lines  parallel  with  the  first  two  of  these  directions 
but  the  head  grain  may  be  so  poor  that  regular  rectangular 
blocks  can  be  quarried  only  with  great  expense.  (See  Fig. 
20.) 

In  the  granite  quarries  in  Vermont  the  term  lift  is  often 
used  for  the  first  of  these  directions,  rift  for  the  second  and 
grain  for  the  third.  (See  Fig.  21.) 

According  to  T.  Nelson  Dale  the  rift  in  granite  is  an  obscure 
microscopic  foliation  which  may  be  either  vertical,  or  nearly 


28  BUILDING    STONES    AND    CLAYS 

so,  or  horizontal,  along  which  the  stone  splits  more  easily 
than  in  any  other  direction.  The  grain  is  a  foliation  in  a 
direction  at  right  angles  to  the  rift  along  which  the  rock  splits 
with  a  facility  second  only  to  that  of  the  fracture  along  the 
rift. 

J.  F.  W.  Carpenter  attributed  rift  to  a  parallel  arrangement 
of  the  various  mineral  particles  in  a  building  stone.  R.  S. 
Tarr  in  his  paper  entitled  "  The  Phenomena  of  Rifting  in 
Granite,"  states  that  rift  consists  of  microscopic  faults,  most 
of  which  meander  across  feldspar  and  quartz  alike,  although 
some  go  around  the  quartz  particles  rather  than  across  them. 
In  the  feldspars  rift  usually  follows  the  cleavage.  These 
minute  faults  are  lined  with  microscopic  fragments  of  the 


-GRAItN 


RIFT 

Fig.  21. — Drawing  to  explain  lift  as  often  used  by  Vermont  granite 
quarrymen.  Drawing  by  C.  H.  Richardson. 

minerals  they  traverse  and  some  of  them  send  off  short,  minute 
diagonal  fractures  on  either  side.  In  the  orbicular  granite  of 
Craftsbury,  Vermont,  the  rift  usually  passes  around  the 
orbnles  rather  than  across  them.  The  rift  also  does  not 
traverse  the  basic  dikes  associated  with  the  granites  in  the 
Jones  Brothers  quarry,  Barre,  Vermont,  or  the  quarries  of 
the  Woodbury  Granite  Company  on  Robeson  Mountain, 
Woodbury,  Vermont. 

G.  I.  Finlay  in  his  paper  entitled  "The  Granite  Area  of 
Barre,  Vt.,"  states  that  the  pronounced  cracks  which  seem  to 
cross  from  one  crystal  of  quartz  to  another,  without  inter- 
ruption, are  an  indication  of  pressure  phenomena  in  the 
magma  after  its  consolidation. 

The  presence  of  good  rift  and  grain  is  an  important  factor 


PHYSICAL  PROPERTIES  AND  WEATHERING     29 

in  the  stone  industry,  for  it  materially  reduces  the  cost  of 
production  of  the  finished  product. 

Compression." — Compressive  strength  in  building  stones 
depends  upon  the  mineral  composition,  the  size  of  the 
individual  constituents  and  their  state  of  aggregation.  The 
tests  are  made  with  one  inch,  or  five  inch,  cubes  and  stated 
in  terms  of  pounds  per  cubic  inch.  The  granites  because  of 
their  oft  interlocking  crystals  and  the  small  interstitial  spaces 
between  the  individual  minerals  have  a  high  compressive 
strength.  In  good  granites  it  varies  from  15,000  Ib.  to  33,000 
Ib.  to  the  cubic  inch.  In  the  marbles  desired  for  structural 
work  it  varies  from  13,000  Ib.  to  17,000  Ib.  to  the  cubic  inch. 
Some  of  the  dolomites,  however,  like  those  of  Staten  Island, 
N.  Y.,  reach  24,000  Ib. 

Transverse  Strength. — This  is  the  load  which  ;a  bar  of  stoner 
supported  at  both  ends,  is  able  to  withstand  without  breaking. 
It  is  measured  in  terms  of  the  modulus  of  rupture,  which 
represents  the  force  necessary  to  break  a  bar  one  inch  cross 
section,  resting  on  supports  one  inch  apart,  the  load  being 
applied  in  the  middle.  Stones  in  buildings  are  more  apt  to 
be  broken  transversely  than  crushed. 

THE  WEATHERING  OF  BUILDING  STONES 

The  term  weathering  of  building  stones  embraces  all  the 
chemical,  mineralogical  and  structural  changes  that  a  stone 
undergoes  when  exposed  to  the  destructive  influences  in  the 
atmosphere.  It  involves  something  more  than  the  ordinary 
changes  effected  in  rock  masses  in  the  processes  of  normal 
disintegration.  The  destructive  agencies  may  be  catalogued 
as  chemical  and  mechanical.  (See  Figs.  22  and  23.) 

Chemical. — Pure  water  has  but  little  if  any  solvent  effect 
upon  building  stone.  Water  is  seldom  pure.  It  carries 
dissolved  oxygen  and  carbon  dioxide.  It  partially  dissolves 
the  more  soluble  materials  with  the  liberation  of  colloidal 
silica,  and  the  formation  of  the  carbonates  of  calcium,  mag- 
nesium, iron  and  the  alkalies.  The  lime,  magnesia,  alkali 
salts  and  much  of  the  dissolved  silica  remain  in  solution  and 
are  washed  away.  The  iron  carbonate  is  unstable.  In  its 
oxidation  it  forms  the  visible  rusty  coating  or  precipitate  of 
ferric  hydroxide  that  renders  buildings  once  beautiful  now 
unsightly. 

According  to  W.  P.  Headden  the  solutions  formed  by  the 
decomposition  of  the  feldspathic  rocks  show  a  far  greater 
change  in  the  insoluble  minerals  than  is  apparent  to  the 


30 


BUILDING    STONES   AND    CLAYS 


casual  observer.  He  treated  orthoclase  for  a  considerable 
period  of  time  with  water  charged  with  carbon  dioxide  and 
obtained  a  solution  which  upon  evaporation  gave  a  residue 
that  carried  over  40  per  cent  of  silica. 

Another  phase  of  the  process  is  represented  in  the  hydration 
of  the  undissolved  residues.  The  iron  minerals  form  limonite, 
the  feldspars  are  transferred  into  kaolinite,  and  the  mag- 
nesium minerals  pass  into  talc  or  serpentine.  This  double 
process  of  solution  and  hydration  is  accompanied  by  an 
increase  in  volume  which  may  assist  in  effecting  disintegration. 


Fig.  22. — Ovoidal  block  of  fine  statuary  granite  produced  by 
weathering.  Redstone  quarry,  Westerly,  Rhode  Island.  By  courtesy 
of  the  U.  S.  Geological  Survey. 

According  to  J.  Hirschwald  the  solvent  effect  of  pure  rain 
water  upon  the  compact,  fine  grained,  Solenhofen  limestone 
would  give  a  reduction  in  volume  of  0.85  millimetre  in  a 
century. 

One  decidedly  injurious  constituent  in  the  atmosphere 
results  from  the  large  consumption  of  coal.  The  fuel  often 
carries  sulphur  in  combination  with  iron  as  the  mineral 
pyrite.  In  the  combustion  of  the  coal  the  sulphur  is  burned 
to  sulphurous  acid  which  ultimately  becomes  sulphuric  acid. 
This  corrosive  dissolves  out  the  lime  as  calcium  sulphate 


PHYSICAL  PROPERTIES  AND  WEATHERING     31 

which  may  crystallize  as  gypsum  and  in  doing  so  assist  in 
the  disruption  of  the  surface  layers  of  building  stone.  The 
acid  also  attacks  the  mortar  and  cement  with  which  the  blocks 
of  stone,  terra  cotta,  or  brick  are  bound  together  in  the 
finished  structure.  This  effect  is  often  observed  in  the  upper 
courses  of  chimneys.  Nitric  acid,  hydrochloric  acid  and 


"**• 


Fig.  23. — Polished  slab  of  biotite  granite,  showing  a  dead  seam. 
Photo,  by  C.  H.  Richardson. 

ammonia  have  also  been  observed  in  the  atmosphere.  Their 
presence  everywhere  accelerates  the  decomposition  of  building 
stone. 

Coal  combustion  without  smoke  consumption  results  in 
supplying  the  atmosphere  with  unburned  carbon  and  tarry 
particles  that  give  rise  to  the  smoke  nuisance  of  large  manu- 
facturing cities.  Not  only  does  the  smoke  soon  render  the 
building  unclean  or  unsightly  but  it  acts  as  a  carrier  or  holder 


32  BUILDING    STONES    AND    CLAYS 

of  deleterious  gases.  In  cities  like  London  where  fogs  are 
prevalent  countless  particles  of  condensed  moisture  carry 
dissolved  gases  to  the  surfaces  of  stone  structures  and  leave 
them  there  for  many  clays  to  execute  their  work  of  corrosion. 
Snow  often  carries  a  higher  percentage  of  gases  than  rain  and 
the  lodgment  of  snow  upon  the  sides  of  buildings,  ledges  and 
moldings  favors  disintegration. 

In  cities  scattered  along  coast  lines  and  subject  to  salt 
laden  sea  breezes  the  sodium  chloride  increases  the  solvent 
action  of  water  on  carbonates  and  sulphates  and  aids  also  in 
the  attack  upon  lime  silicates. 

Vegetation. — Vegetation  exerts  a  profound  influence  in  the 
decomposition  of  rocks.  Microscopic  algae,  mosses  and 
lichens  rind  lodgment  on  buildings  and  aid  in  rock  decay. 
They  retain  moisture  and  make  the  surface  beneath  them 
damp.  Their  rootlets  and  roots  penetrate  into  the  surface  of 
rocks  along  the  lines  of  least  resistance  as  they  expand  in  the 
process  of  growth.  Their  roots  contain  organic  acids  which 
serve  as  solvents  for  minerals.  The  limestones  and  marbles 
appear  to  suffer  more  than  the  granites  from  the  invasion  of 
lichens.  According  to  E.  Bachmann  this  penetration  is  made 
regardless  of  the  cleavage  planes  in  the  calcite.  In  the  field, 
rocks  of  great  strength  and  durability  are  often  covered  with 
lichens. 

Bacteria. — Even  such  low  forms  of  life  as  bacteria  materially 
influence  the  decomposition  of  rocks.  They  draw  their  nour- 
ishment from  the  nitrogen  compounds  brought  down  in  storms 
and  convert  the  ammonia  into  nitric  acid  which  in  turn  serves 
as  solvent  for  mineral  substances. 

Physical  Agencies. — Building  stones  as  a  rule  are  low  in 
their  conduction  of  heat  and  in  their  elasticity.  When  heated 
they  expand  but  their  contraction  may  not  be  to  normal.  This 
permanent  increase  in  dimensions  is  termed  permanent  swell- 
ing. Many  tests  have  been  made  with  rock  bars  20  inches 
in  length,  heated  from  32 °F.  to  the  boiling  point  of  water  and 
then  cooled  to  normal  temperature.  The  results  obtained 
for  granites  were  .009  inch ;  marble,  .009  inch ;  limestones, 
.007  inch ;  sandstones,  .0047  inch.  Small  as  this  expansion 
seems  to  be  it  profoundly  affects  the  decomposition  of  rocks. 
According  to  J.  D.  Dana  the  influence  of  the  sun's  rays  upon 
Bunker  Hill  monument  causes  a  pendulum  when  suspended 
from  the  top  to  describe  an  irregular  ellipse  nearly  half  an 
inch  in  its  greatest  diameter.  The  shaft  was  erected  of 
Quincy  granite  in  1825.  It  is  30  feet  square  at  the  base  and 
221  feet  high. 


PHYSICAL  PROPERTIES  AND  WEATHERING     33 

Frost. — The  lowering  of  the  temperature  in  rocks  below  the 
freezing  point  of  water  causes  the  absorbed  water  to  expand 
upon  solidification.  This  expansion  throws  off  small  scales 
from  the  surface  or  may  even  fracture  large  blocks.  Accord- 
ing to  James  Geikie  if  a  porous  sandstone  becomes  thoroughly 
saturated  with  water  and  the  temperature  falls  below  zero 
the  pressure  of  the  expansive  force  as  the  water  solidifies  is 
equal  to  a  column  of  ice  one  mile  high.  Building  stones  then 
in  northern  climates  where  the  temperature  often  falls  to  zero 
are  rapidly  decomposed. 

Friction. — The  effects  of  friction  in  the  constant  abrasion 
of  building  stones  is  most  pronounced  on  sidewalks.  The 
undulations  in  the  surface  of  the  walks  of  many  large  cities. 
illustrate  the  rapid  wearing  away  of  the  softer  portions  of  the 
rock  mass  and  the  greater  resistance  of  the  harder  areas.. 
The  convexities  and  the  concavities  in  the  treads  of  many 
stairways  in  city  hotels  are  evidences  of  this  same  type  of 
abrasion.  In  some  large  libraries  the  only  entrance  is  over 
a  single  threshold  of  sandstone  which  wears  away  rapidly 
with  the  daily  visitations.  Windows  in  sandstorm  zones  are 
often  rendered  non-transparent  by  the  effects  of  wind-blown 
sand.  This  feature  is  especially  noticeable  in  many  of  the: 
western  states.  It  has  also  been  observed  in  many  instances 
along  the  eastern  coast  of  New  England.  In  many  cemeteries 
where  markers  and  monuments  face  in  the  direction  of  the 
prevailing  winds,  the  inscriptions  become  illegible  from  the 
same  cause. 

Induration. — When  a  building  stone  is  first  quarried  it  is 
saturated  with  quarry  water.  This  facilitates  the  working  of 
the  stone  and  makes  possible  the  loss  of  material  by  shipment 
when  the  stone  is  frozen.  The  quarry  water  holds  in  solution, 
or  suspension,  an  appreciable  amount  of  the  cements  that 
bind  the  individual  grains  together.  Upon  exposure  to  the 
atmosphere  this  moisture  is  drawn  to  the  surface  by  capillary 
attraction  and  evaporated.  The  lime,  iron,  silica,  and  clayey 
matter  are  left  as  a  cement  protecting  the  exterior  of  the 
stone.  Honing  and  rescouring  of  objects  of  art  after  the 
quarry  water  has  evaporated  tends  to  render  the  destruction 
of  the  stone  more  rapid.  For  the  same  reason  blocks  for 
massive  structures  should  be  so  wisely  selected  that  they  will 
not  need  re-dressing. 

Life. — The  life  of  a  building  stone  signifies  the  length  of 
time  that  -fnay  elapse  before  the  resulting  stone  structure 
will  so  discolor  or  disintegrate  as  to  necessitate  repairs.  Some 
of  our  cities  are  replete  with  structures  which  contain  blocks 


34  BUILDING    STONES    AND    CLAYS 

of  stone  that  appear  dead  within  five  years  from  the  com- 
pletion of  the  structure.  A  re-dressing  of  such  a  block  renders 
a  brighter  appearance  for  only  a  brief  time  and  is  always 
unsightly.  Such  instances  might  be  easily  avoided  by  a 
judicious  selection  of  the  stone  during  the  process  of  con- 
struction. The  life  varies  widely  with  the  different  types. 
A.  Julien  has  carefully  studied  these  factors  in  many  stone 
structures  in  New  York  City  with  the  following  results : 

Coarse  brownstone  5-  15  years 

Fine-laminated  brownstone 20-  50  years 

Compact  brownstone 100-200  years 

Coarse  fossiliferous  limestone... 20-40  years 

Coarse  dolomitic  marble.. 30-  50  years 

Fine  dolomitic  marble 60-  80  years 

Fine-grained  marble  50-100  years 

Granite 75-200  years 

Quartzite  75-200  years 

According  to  J.  A.  Howe  the  stone  castles  of  the  British 
Isles  possess  many  blocks  of  stones  whose  tool  marks  have 
been  perfectly  preserved  for  more  than  700  years.  It  would 
therefore  appear  that  a  home  might  be  constructed  of  an  iron 
free  quartzite  that  would  last  for  a  thousand  years. 

Selection  of  Building  Stone. — The  following  rules  may  be 
stated  as  an  aid  in  selecting  the  better  types  of  structural 
stone  : 

(1)  Select  a   stone   that   will   resist    well   wide   ranges   of 
temperature.     The  author  has  twice  read   a  thermometer  at' 
62°  below  zero  in  northern  New  England  and  98°  above  zero 
is    frequently    recorded    in    the    same    field.     The    range    of 
temperature  which  the  stone  must  stand  is  160°.     The  coquina 
of  Florida  and  the  hornblende  granite  of  Syene,  Egypt,  would 
rapidly  disintegrate  in  such  environment. 

(2)  Select  a   stone  that  will   stoutly   resist   the   corrosive 
effects    of    the   acids    and   gases   of   the   atmosphere.     Where 
large  quantities  of  acid  fumes  are  constantly  distilled  into  the 
atmosphere  a  stone  with  a  calcareous  cement  will  disintegrate 
far  more  rapidly  than  one  whose  cement  is  silica. 

(3)  Select  a   stone   writh    high   compressive   strength   and 
elasticity. 

(4)  Select  a  stone  with  large  resistance  to  abrasion. 

(5)  Select    a    stone    that    always    shows    a    clean,    fresh 
fracture. 

(6)  Select  a  stone  that  gives  a  clear  ring  when  struck  with 
a  hammer. 


PHYSICAL  PROPERTIES  AND  WEATHERING     35 

(7)  Select  a  stone  that  is  fine  grained  and  of  even  texture. 

(8)  Select  a  stone  with  low  porosity. 

(9)  Select  a  stone  with  a  siliceous  cement,  if  possible. 

(10)  Season   a   stone   for  a  year   before   setting   it  in  its 
•permanent  position.    Quarry  owners  will  object  to  this  method 
of    procedure!     Yet    knowledge    should    be    available    of    the 
relative  life  of  the  stone.     If  oxidizable  sulphides  are  present, 
or  the  carbonate  of  iron,  the  stone  will  begin  to  disintegrate 
and  change  its  color  within  a  year  from  the  time  it  is  quarried. 

METHODS  OF  TESTING  BUILDING  STONE 

Color  Test. — The  purpose  of  this  test  is  to  ascertain  the 
permanency  of  color  in  any  building  stone.  All  rocks  con- 
taining the  carbonate  of  iron  or  the  sulphide  of  iron  will  suffer 
a  change  in  color  on  exposure  to  the  atmosphere  due  to  an 
oxidation  of  the  iron  content. 

The  presence  of  sulphides  may  be  detected  in  the  laboratory 
by  the  hepar  test.  The  effect  of  an  artificial  atmosphere  in 
accelerating  oxidation  has  been  carefully  worked  out  by  J.  A. 
Dodge.  Rectangular  blocks  about  an  inch  in  diameter  are 
dried  in  a  water  bath  until  all  of  the  absorbed  moisture  is 
expelled.  They  are  then  placed  on  glass  shelves  in  an  air- 
tight chamber  with  open  bottles  of  concentrated  HC1  and 
HNO3  in  close  proximity  to  MnO2.  The  fumes  from  the  acids 
together  with  the  chlorine  formed  by  the  action  of  the  HC1 
on  the  MnO2  exert  a  powerful  oxidizing  and  corrosive  effect 
on  the  samples.  After  seven  weeks  the  samples  are  removed, 
washed  and  the  change  in  color  noted. 

Corrosion  Test. — This  test  is  useful  for  all  calcareous  rocks. 
Inch  cubes  are  suspended  in  water  and  subjected  at  intervals 
to  the  action  of  washed  carbonic  acid  gas.  The  experiment 
should  be  continued  for  six  weeks.  The  specimen  should  then 
be  removed,  -washed,  dried  and  weighed.  By  this  test  lime- 
stones sometimes  suffer  a  loss  of  more  than  1  per  cent  of 
weight.  Quartzites  whose  cement  is  silica  and  massive 
granites  that  show  no  effervescence  with  HC1,  due  to  small 
calcite  content,  are  not  appreciably  affected  by  the  experiment. 

Abrasion  Test. — The  resistance  to  abrasion  can  be  esti- 
mated by  grinding  a  small  sample  on  a  common  grinding 
bed.  Much  depends  however  on  the  weight  applied  during 
the  grinding  and  the  constancy  of  the  supply  of  crushed 
emery  or  sand  used  for  the  abrasive.  Soft  rocks  like  the 
limestones  will  wear  away  rapidly.  If  they  contain  hard 
spots  they  will  not  wear  uniformly. 


36  BUILDING    STONES   AND    CLAYS 

Absorption  Test. — The  tests  to  determine  the  absorptive 
power  of  building  stones  is  perhaps  the  most  important  and 
conclusive  but  not  always  absolutely  reliable. 

To  determine  the  absorption  from  a  damp  atmosphere  J.  A. 
Dodge  placed  the  samples  to  be  tested  in  the  cells  of  a  hot- 
water  bath  for  several  days.  After  the  hygroscopic  moisture 
of  the  samples  was  expelled  the  samples  were  desiccated  over 
H2SO4  and  weighed.  They  \vere  then  placed  on  glass  shelves 
in  a  pan  of  \vater,  covered  with  a  tight  cylinder  and  allowed 
to  stand  for  seven  weeks  at  a  temperature  ranging  from  60 
to  70  degrees  F.  and  then  weighed.  The  absorptive  power 
varied  from  .03  per  cent  to  3.94  per  cent. 

.The  amount  of  absorption  by  soaking  is  generally  deter- 
mined by  carefully  drying  and  weighing  2-inch  cubes,  then 
immersing  them  in  \vater  in  a  porcelain  dish  until  thoroughly 
saturated.  The  cubes  are  then  removed  and  \veighed.  The 
percentage  of  absorption  varies  from  .83  to  10.06. 

Freezing  Test. — The  best  method  to  pursue  \vhere  possible 
is  to  subject  the  samples  to  repeated  freezings  and  thawings 
and  thereby  determine  the  loss  in  weight.  Where  this  test 
is  found  to  be  impractical  inch  cubes  may  be  subjected  to  the 
influence  of  a  boiling  solution  of  Na2SO4  for  half  an  hour  and 
then  allowed  to  dry.  During  the  drying  the  absorbed  salt 
crystallizes  and  expands.  The  process  may  be  repeated  lor 
six  or  eight  days.  The  experiment  is  not  altogether  reliable 
for  the  sulphate  of  soda  may  give  rise  to  free  Na2O  which 
weakens  the  cohesion  of  the  sample. 

Expansion  and  Contraction  Test. — These  tests  are  necessary 
that  the  builder  may  make  proper  allowance  for  expansion 
in  parapet  walls  and  similar  situations,  and  because  the 
tenacity  of  a  stone  is  weakened  by  expansion  and  contraction. 

The  tests  employed  by  the  Ordinance  Department  of  the 
U.  S.  Army  consisted  in  placing  20  inch  bars  of  stone  in  baths 
of  water  at  32° P.,  then  in  water  at  212°F.  and  then  cooling 
quickly  in  water  at  32 °F.  Samples  thus  tested  do  not  return 
to  normal  dimensions  but  show  a  permanent  swelling. 

Fire  Resisting  Test. — In  the  experiments  carried  out  by  J- 
A.  Dodge  the  samples  were  heated  in  a  muffle  furnace  to  a  red 
heat  and  then  removed  and  cooled.  The  experiment  was 
repeated.  The  samples  were  then  heated  to  a  dull  redness  and 
immersed  in  \vater.  Most  building  stones  will  crack  or 
crumble  under  such  treatment  and  the  test  seems  too  severe 
for  practical  purposes.  For  other  fire  resisting  tests  ,  see 
N.  Y.  State  Mus.  Bull.  No.  100;  p.  16. 


PHYSICAL  PROPERTIES  AND  WEATHERING     37 

Compression  Test. — The  sample  to  be  tested  is  sometimes 
cut  in  1-inch  cube,  sometimes  2-inch  cube  and  sometimes  in 
b-inch  cube.  The  smoothed  faces  are  placed  between  steel 
plates  and  the  pressure  applied.  The  pressure  is  relieved  at 
the  first  sign  of  breaking  in  the  sample  and  the  weight  of 
pressure  recorded.  The  resistance  is  increased  with  the  in- 
creasing dimensions  of  the  cubes  tested.  The  resistance  to 
compression  of  each  type  of  building  stone  is  given  under 
its  respective  caption  in  the  subsequent  chapters. 

Elasticity  Test. — To  determine  the  elasticity  of  a  stone  a 
sample  24-in.  by  6-in.  by  4-in.  is  selected.  The  power  is 
applied  from  the  ends  and  the  compressibility  measured  with 
a  micrometer.  The  stone  shows  a  permanent  set  from  which 
it  does  not  recover. 

Shearing  Test. — In  this  test  prisms  of  stone  are  supported 
at  each  end  by  blocks  6  inches  apart  and  subjected  to  pres- 
sure applied  by  means  of  a  plunger.  The  plunger  has  a  face 
5  inches  in  width  and  exerts  a  force  in  all  directions.  The 
strain  is  like  that  exerted  in  many  parts  of  a  building. 

Specific  Gravity  Test. — The  small  sample  to  be  tested  is 
first  weighed  in  air,  then  in  water.  The  general  formula  is 

specific  gravity   =  ,.    This  result  multiplied  by  62.5,  the 

weight  of  a  cubic  foot  of  water,  gives  the  weight  of  a  cubic 
foot  of  any  stone. 

For  a  fuller  description  of  the  methods  of  testing  building 
stone  the  reader  is  referred  to  pp.  45?  to  483  inclusive  in 
"  Stones  for  Building  and  Decoration,"  by  G.  P.  Merrill. 


CHAPTER  III 

GRANITES 

Definition. — A  granite  is  a  holocrystalline  igneous  rock 
whose  essential  minerals  are  quartz  and  orthoclase,  usually 
with  muscovite  or  biotite,  or  both,  present,  or  hornblende, 
more  rarely  augite,  or  both.  There  is  generally  present  a 
feldspar  containing  both  sodium  and  calcium.  If  a  body  of 
granite  subsequent  to  its  crystallization  has  been  subjected 
to  sufficient  pressure  to  produce  schistosity,  or  parallelism 
of  the  ferromagnesian  minerals,  it  is  called  by  the  quarryman 
a  granite  gneiss.  As  gneisses  differ  widely  in  their  origin 
they  are  reserved  for  discussion  under  another  caption. 

Origin. — Granite  is  generally  recognized  to  be  of  irruptive 
origin.  It  represents  the  crystallization  of  an  acid  magma 
under  great  pressure  and  at  a  dull  red  heat.  The  magma 
contained  superheated  water  and  came  slowly  from  the  zone 
of  fiowage  in  the  interior  of  the  earth  toward  the  surface  but 
did  not  flow  out  over  the  surface.  Thousands  of  feet  of 
overlying  strata  are  necessary  to  prevent  a  rapid  cooling  of  the 
mass  and  its  extrusion  upon  the  surface  as  lava,  also  "  to  resist 
its  pressure  by  its  own  cohesion  and  powerfully  to  compress 
it  by  its  own  gravity."  The  presence  of  liquid  carbon  dioxide 
in  the  cavities  of  the  necessary  quartz  is  an  indisputable  proof 
that  granite  forms  under  great  masses  of  supernatant  strata. 
These  terranes  must  be  removed  by  erosion  in  order  to  bring 
the  granite  formation  into  view.  The  fact  that  granite 
contains  minerals  that  lose  their  physical  properties  at  tem- 
peratures exceeding  a  dull  red  heat  is  proof  that  it  crystallizes 
at  temperatures  comparatively  low.  If  the  magma  had  been 
extruded  upon  the  surface  as  lava  it  would  have  cooled  so 
rapidly  that  few  if  any  individual  minerals  would  have  formed 
and  the  product  would  have  been  a  volcanic  glass.  Slow 
cooling  is  necessary  for  complete  individualization.  The 
study  of  many  microscopic  slides  reveals  the  order  of 
crystallization.  If  the  accessory  minerals  apatite  and  zircon 
are  possible  in  the  magma  they  appear  among  the  earliest 
solidifications.  The  ferromagnesian  minerals  crystallize  be- 
fore the  feldspars,  while  quartz,  which  is  the  most  acidic  of 

38 


GRANITES  39 

all  the  minerals  in  granite,  is  the  last  to  solidify.  Granite  may 
also  result  from  the  metamorphisni  of  feldspathic  sediments. 

Mode  of  Occurrence.— Granites  occur  in  large  batholiths 
that  have  dissolved  the  overlying  rock  masses  and  made  them 
a  part  of  their  own  composition ;  as  laccoliths  that  have  arched 
the  overlying  strata  upwards;  as  bosses,  stocks,  sills  and 
tortuous  veins. 

Name. — Granites  are  often  named  from  the  prevailing  ferro- 
magnesian  minerals  they  contain.  A  granite  containing 
muscovite  would  be  called  a  muscovite  granite ;  one  containing 
biotite  is  known  as  a  biotite  granite ;  one  containing  both 
muscovite  and  biotite  as  a  muscovite  biotite  granite.  If  a 


Fig.  24. — Polished  disc  of  white  granite,  Bethel,  Vermont.  From 
quarries  of  the  Woodbury  Granite  Company,  Hardwick,  Vermont. 
Photo,  by  C.  H.  Richardson. 

granite  contains  hornblende  it  is  called  a  hornblende  granite; 
if  it  contains  augite  alone  an  augite  granite.  If  both  minerals 
are  present  it  is  called  an  augite  hornblende  granite.  If  tour- 
malines are  present  in  considerable  quantity  displacing  the 
normal  ferromagnesian  minerals  it  is  called  a  tourmaline 
granite.  Tourmalines  may  be  formed  by  some  mineralizing 
agency  during  magmatic  crystallization  or  by  pneumatolysis 
at  the  expense  of  mica  and  feldspar. 

Economic  Classification. — There  are  several  different  ways 
of  classifying  granites  from  an  economic  standpoint. 

(1)  If  the  classification  is  based  upon  color,  it  is  dependent 
upon  the  color  of  the  prevailing  feldspar,  or  upon  the  effect 


40  BUILDING    STONES    AND    CLAYS 

of  the  micas  on  the  granite  as  a  whole.  The  granite  is  called 
red  if  the  orthoclase  is  red.  Pink,  if  the  orthoclase  is  pink  or 
flesh  colored.  Green,  if  the  effect  of  the  feldspar  and  the 


Fig.    25. — Polished    disc   of    fine    grained    gray    granite,    Barre,   Ver- 
mont.    Photo,  by  C.  H.  Richardson. 


Fig.  26. — Polished  disc  of  medium   grained  gray   granite,   Newport, 
Vermont.     Photo,  by  C.   H.   Richardson. 

ferromagnesian  minerals  combined  produces  that  color.  Gray, 
light  or  dark,  dependent  upon  the  amount  and  kind  of  mica 
that  is  present.  (See  Fig.  24.) 


GRANITES 


41 


(2)  The  basis  of  classification  may  be  made  upon  texture. 
If  the  crystals  are  exceedingly  fine,  less  than  .2  inch  in 
diameter,  the  stone  is  called  fine  grained ;  if  of  medium  size, 
between  .2  and  .4  inch  in  diameter,  medium ;  if  coarse,  more 
than  .4  inch  in  diameter,  coarse  grained ;  or  if  phenocrysts  of 
appreciable  size  appear,  the  stone  is  called  porphyritic.  (See 
Fig.  25.) 


Fig.  27. — Christian  Science  Church,  Concord,  New  Hampshire,  built 
of  Concord  granite.  Photo,  copyrighted  by  Kimball  and  Son,  Con- 
.cord,  N.  H.,  and  published  by  their  courtesy. 


42  BUILDING    STONES   AND    CLAYS 

(3)  These  two  features  may  be  used  together  in  classifica- 
tion.    A    fine    grained    red    granite    might   be    the    result.     A 
porphyritic  green  granite,  or  a  medium  grained  gray  granite. 
(See  Fig.  26.) 

(4)  Granites  are  often  classified  in  the  commercial  world 
from  the   standpoint   of  use.     If  a  granite  is  better   adapted 
for    massive    structures    than    any    other    use    it    is    called    a 
constructional  granite.     If  its  qualities  render  the  stone  better 
suited  for  cemetery  work  than   any  other  it  is  called   monu- 
mental or  inscriptional.     If  it  is  well  suited  for  base  boards, 
panels  and   pillars  where  it  is   not  exposed  to  the   corrosive 
effects  of  the  atmosphere  it  is  called  decorative.     If  the  granite 
is  sufficiently  fine  grained  for  excellent  work  in  the  construc- 
tion   of   statues   and   statuettes    it   is   called   statuary  granite. 
(See  Figs.  27  and  28.) 

Geographical  Distribution. — The  Appalachian  belt  presents 
many  occurrences  of  granites  arranged  in  a  line  practically 
parallel  with  the  Atlantic  Coast.  A  second  belt  is  roughly 
parallel  with  the  Pacific  Coast.  A  third  belt  appears  along 
the  axis  of  the  Rocky  Mountains.  It  might  be  called  the  Cor- 
dilleran  belt.  A  fourth  area  appears  in  the  neighborhood  of 
the  Great  Lakes  between  Lake  Michigan  and  Lake  Superior, 
and  to  the  north  of  Lake  Superior.  Rather  than  discussing 
these  occurrences  by  districts  the  author  prefers  to  take  up 
the  more  important  states  in  alphabetical  order. 

AMERICAN    GRANITES 

California. — According  to  G.  P.  Merrill  the  first  stone  house 
in  San  Francisco  was  built  out  of  stone  brought  from  China. 
Later  granite  blocks  were  secured  from  Scotland  and  Quincy, 
Mass.  In  1864  the  granite  quarries  at  Penrhyn  and  Rocklin 
in  Placer  county  were  opened  up.  This  tract  alone  com- 
prises some  680  acres.  Blocks  100  feet  long,  50  feet  wide, 
and  10  feet  thick  have  been  quarried. 

According  to  J.  J.  Jackson  the  Penrhyn  stone  is  a  fine 
grained  hornblende  granite  susceptible  of  a  good  polish.  He 
gives  the  mineralogical  composition  as  quartz,  orthoclase, 
plagioclase,  hornblende,  biotite,  with  accessory  microscopic 
apatite  and  magnetite.  The  Rocklin  stone  is  lighter  in  color 
for  muscovite  replaces  the  hornblende.  Granites  are  also 
quarried  in  Sacramento  County.  (See  Figs.  29,  30  and  31.) 

Colorado.— The  granite  industry  of  Colorado  is  quite 
largely  dependent  upon  the  industrial  development  of  the 


GRANITES 


I.  -3 

00.  O 

<M  tn 


44 


BUILDING    STONES   AND    CLAYS 


state.     The  cost  of  transportation  is  high  for  building  stones 
both  in  an  easterly  and  in  a  westerly  direction.     The  author 


Fig.  29. — Polished  slab  of  hornblende  granite,   Penrhyn,  California. 
Photo,  by   C.   H.   Richardson. 


Fig.    30. — Polished    slab    of    light    gray    granite    from    near    Granite 
Peak,  Raymond,  California.     Photo,  by  C.  H.  Richardson. 


has  examined  several  quarries  of  fine  grained  gray  granite  at 
Georgetown    and    Lawson    in    Clear    Creek    County.     These 


GRANITES 


45 


granites  takes  a  fine  polish  and  are  well  suited  for  construc- 
tional work.  A  coarse  red  granite  is  quarried  to  some  extent 
in  Jefferson  County  at  Platte  Canon.  A  gray  granite  of 
superior  quality  is  quarried  at  Beaver  Creek,  Gunnison 
County.  The  State  Capitol  at  Denver  was  built  of  this  stone. 
(See  Fig.  32.) 

Connecticut. — Granites  are  extensively  quarried  in  five 
counties  in  Connecticut.  These  are  Litchfield,  Fairfield, 
Middlesex,  New  Haven  and  New  London  Counties.  The 


I 


* 


Fig.  31. — Declez  granite  quarry,  Declez,  San  Bernardino  County, 
California.  Photo,  by  T.  C.  Hopkins. 

granites  are  usually  finer  grained,  lighter  in  color,  than  the 
granites  of  northern  New  England.  Frequently  Connecticut 
granites  can  be  recognized  by  these  ear  marks. 

The  constructional  granitic  rocks  of  Connecticut  are  a 
medium  to  coarse  biotite  granite  of  medium  reddish  gray 
color  quarried  at  Stonington ;  a  medium  to  coarse  biotite 
granite  gneiss  of  reddish  gray  color  quarried  at  Bran  ford  ;  a 
coarse  biotite  granite  gneiss  of  dark  reddish  gray  color 


46 


BUILDING    STONES   AND    CLAYS 


GRANITES  47 

quarried  at  Branford ;  a  medium  biotite  granite  gneiss  of  red- 
dish gray  color  quarried  at  Guilford ;  a  quartz  monzonite  of 
fine  grain  and  light  gray  color  at  Bristol ;  a  coarse  mica  dionte 
gneiss  of  dark  bluish  gray  color  at  Greenwich ;  granite  gneisses 
are  also  quarried  at  Lyme,  Norfolk,  Roxbury  and  Torrington, 
Connecticut. 

The  monumental  granite  rocks  are  chiefly  quartz  mon- 
zonites.  They  are  quarried  at  Waterford,  Groton,  Stoning- 
ton  and  Thomaston.  In  color  they  are  medium  dark  gray, 
medium  greenish  gray,  slightly  bluish  gray  and  medium  bluish 
gray. 


Fig.  33.  —  Polished  slab  of  Stony  Creek  granite,  Stony  Creek, 
Connecticut.  Photo,  by  C.  H.  Richardson. 

Inscriptional  quartz  monzonites,  shading  in  color  from 
medium  to  dark  gray  are  quarried  at  Groton,  Stonington  and 
Waterford. 

Biotite  granite  gneisses,  used  for  curbing  and  trimming, 
shading  in  color  from  a  buff  gray  to  a  dark  bluish  gray,  are 
quarried  at  Balton,  Glastonbury  and  Waterford.  (See  Fig.  33.) 

Delaware. — The  granite  industry  of  Delaware  is  restricted 
to  a  few  gneissoid  rocks  in  the  neighborhood  of  Wilmington. 
Their  use  is  for  construction  locally. 

Georgia. — The  granites  of  Georgia  fall  into  two  distinct 
classes; — The  granite  proper  and  the  gneissoid  granites. 
They  are  usually  fine  grained,  even  textured,  susceptible  of  a 


48 


BUILDING    STONES   AND    CLAYS 


good  polish  and  suited  for  both  construction  and  monumental 
work.  The  former  class  occurs  in  the  Elberton-Oglesby- 
Lexington  area,  the  Fairburn-Newman-Greenville  area  and 
the  Stone  Mountain  area.  The  latter  class  occurs  in  the 
Lithonia-Conyers-Lawrenceville  area.  A  coarse  grained, 
porphrytic,  biotite  granite  occurs  in  the  Sparta  area. 

Maine. — The  granite  industry  of  Maine  may  be  said  to  have 
its  center  in  Penobscot  and  Blue  Hill  bays  and  the  islands 
encircling  them.  More  than  K30  quarries  and  prospects  have 
been  opened  and  most  of  these  are  along  the  seaboard,  on 


Fig.    o4. — King    Chapel,    Bowcloin    College,    Brunswick,    Maine.      By 
courtesy  of  Bowcloin  College. 

islands,  or  near  bays  or  navigable  rivers.  This  area  which 
includes  the  major  portion  of  the  granite  industry  of  the  stite 
comprises  some  1,200  square  miles.  Thirteen  counties  produce 
either  true  granites  or  gneissoid  granites.  These  are  Cum- 
berland, Franklin,  Hancock,  Kennebec,  Knox,  Lincoln, 
Oxford,  Penobscot,  Piscataquis,  Somerset,  Waldo,  Washing- 
ton and  York.  It  is  only  the  quarries  that  the  author 
has  personally  visited  that  will  be  described.  For  a  full  and 
complete  description  of  all  the  quarries  and  prospects  within 
the  state  the  reader  is  referred  to  Bulletin  313  U.  S.  Geological 
Survey,  "  The  Granites  of  Maine,"  by  T.  Nelson  Dale. 


GRANITES 
Cumberland  County 


49 


The  Grant  quarry  is  situated  less  than  three  miles  from 
the  city  of  Brunswick.  It  represents  a  biotite  granite  of 
medium  gray  shade  and  of  even  texture.  The  Chapel  of 
Bowdoin  College  was  built  of  this  stone.  (See  Fig.  34.) 

The  Freeport  quarry  is  situated  within  one  mile  of  Freeport 
station  on  the  Maine  Central  Railroad.  It  represents  a  fine 
grained,  even  textured  granite,  which  bears  both  muscovite 
and  biotite  with  the  latter  mineral  predominating  over  the 
former.  The  polished  tanks  at  Poland  Springs  and  the  front 
of  the  Maine  Building  at  the  Chicago  Exposition  are  of  this 
stone. 


Fig.  35. — Allen  quarry,  west  side  of  Somes  Sound,  Mount  Desert, 
Maine,  showing  lenticular  sheets  crossed  by  a  vertical  diabase  dike, 
faulted  on  the  fourth  sheet  from  the  bottom  of  the  quarry.  By 
courtesy  of  the  U.  S.  Geological  Survey. 


The  Pownal  quarries  are  situated  within  three  miles  of 
Yarmouth  Junction  on  the  Maine  Central  and  Grand  Trunk 
Railroads.  The  stone  is  a  light  gray,  biotite  granite,  of  even 
texture  and  well  adapted  for  monuments  and  constructional 
work. 


.50 


BUILDING    STONES   AND    CLAYS 


Franklin  County 

In  Franklin  County  the  quarries  at  North  Jay  yield  a  white 
granite  which  in  reality  is  of  a  very  light  gray  color.  It  is  a 
biotite-muscovite  granite.  The  stone  is  shipped  largely  to 
the  states  west  of  New  England.  The  Chicago  and  North- 
western building  in  Chicago  is  from  the  North  Jay  quarries. 

Hancock  County 

In  Hancock  County  the  Black  Island  quarries  are  situated 
on  Black  Island.  Two  types  of  granite  occur  on  the  island. 
One  is  a  pale  pinkish  gray,  even  textured  granite,  and  the 
-other  a  somewhat  coarser,  grayish  pink  biotite  granite. 


Fig.  36. — Crabtree  and  Harvey  quarry  in  Sullivan,  Hancock  County, 
Maine,  showing  irregularity  in  the  thickness  of  sheets  owing  to  their 
lenticular  form;  also  9  black  knots.  By  courtesy  of  the  U.  S.  Geologi- 
cal Survey. 

The  McMullen  quarry  is  in  the  town  of  Mount  Desert.  The 
stone  is  a  biotite  granite  of  grayish  buff  color  and  coarse 
grained  texture.  The  United  States  Mint  Building  in  Phila- 
delphia is  of  this  granite.  There  are  many  other  quarries  in 
.Mount  Desert  but  the  most  of  them  are  biotite  granites.  The 


GRANITES 


51 


Graves    Brothers    quarry,    however,    represents   a   hornblende 
granite  that  is  used  only  locally. 

There  are  many  quarries  in  the  town  of  Sullivan.  These, 
with  two  exceptions,  are  biotite  granites  of  gray  color  and 
medium  texture.  The  exceptions  are  the  Sinclair  quarries 
which  represent  a  very  dark  quartz  monzonite  which  contains 


Fig.  37.— -Carving  from  the  light  gray,  fine  textured,  biotite-mus- 
covite  granite  from  the  Stinchfield  quarry,  Hallowell,  Maine,  showing 
adaptation  to  delicate  sculpture.  By  courtesy  of  the  U.  S.  Geological 
Survey. 


both  hornblende  and  biotite,  and  the  Pettee  quarries  which 
consist  of  a  mica-quartz  diorite  of  dark  gray  color  and  medium 
texture.  These  two  quarry  products  are  classified  in  the 
trade  as  black  granites.  (See  Figs.  35  and  36.) 


52  BUILDING    STONES   AND    CLAYS 

Kcnncbcc  County 

In  Kennebec  County  the  granites  of  Hallowell  and  Augusta 
have  been  known  since  1825  when  capital  turned  from  Quincy, 
Mass.,  to  Hallowell,  Maine.  The  granite  is  of  light  gray 
color  and  fine  texture,  with  a  few  phenocrysts  of  feldspar. 
It  is  a  biotite-muscovite  granite  that  has  long  been  justly 
celebrated  for  its  beauty  and  line  working  qualities.  The 
Albany  Capitol,  Hall  of  Records,  N.  Y.,  is  from  the  Stinchfield 
and  Longfellow  quarries,  and  the  General  Slocum  monument 
at  Gettysburg,  Pa.,  is  from  the  Tayntor  quarry.  (See  Figs.  37 
and  38.) 


Fig.    38. — Granite    quarry,    Hallowell,    Maine,    showing    thickness    of 
sheets.     Photo,  by  C.  H.  Richardson. 


The  Fox  Island  granite  comes  not  only  from  Fox  Island 
but  Vinalhaven,  Hurricane,  and  several  adjacent  islands.  The 
majority  of  the  granite  is  a  pinkish-buff,  medium  gray  color, 
coarse,  even  texture.  The  Palmer  quarries,  the  Pequoit 
quarries  and  those  in  the  village  of  Vinalhaven  are  fine 
textured.  These  are  essentially  biotite  granite,  but  the 
Pequoit  quarries  represent  a  biotite-hornblende  granite  and 


GRANITES 


53 


the  Bodwell  black  granite  is  an  olivine  norite  of  black  color 
and  fine  texture.    (See  Figs.  39  and  40.) 


(See  Fig.  41.) 


Lincoln  County 


Oxford  Count \ 

The  Fryeburg  granites  are  in  Oxford  County.  They  are 
muscovite-biotite  granites  of  light  gray  color  and  medium 
texture.  The  Woodstock  granite  from  the  Bryant  quarry  is 
a  quartz-mica  diorite  of  bluish-white  color  and  medium 
texture. 


Fig.    39. — Hurricane    Isle    quarry,    Knox    County,    Maine,    showing 
eastern  end.     By  courtesy  of  the  U.  S.  Geological  Survey. 


Penobscot  County 

The  granite  of  Hermon  Hill,  Penobscot  County,  is  com- 
mercially classified  as  a  black  granite.  In  reality  it  is  an 
altered  diabase  porphyry  with  phenocrysts  of  black  horn- 
blende. The  stone  is  of  a  dark  green  color  and  of  fine  texture. 
The  product  finds  its  best  use  in  dies,  memorial  tablets, 
wainscoting  and  monumental  works.  Lord  Hall  at  the 
University  of  Maine  carries  this  stone. 


54  BUILDING    STONES   AND    CLAYS 

Washington  County 

The  rocks  commercially  classified  as  granites  in  Washington 
County  differ  widely  in  mineral  composition  and  the  uses  to 
which  they  are  well  adapted.  The  Pleasant  River  quarries 
in  the  town  of  Addison  produce  a  hypersthene-olivine  gabbro 
of  black  color  and  medium  texture ;  the  Thornberg  quarries, 
also  in  the  town  of  Addison,  produce  one  granite  identical 
with  the  preceding,  and  another  which  contains  labradorite 
and  no  olivine.  The  town  of  Baileyville  furnishes  a  dark  gray 
norite  of  brilliant  luster.  The  town  of  Calais  produces  a 
black  granite  which  is  a  quartz  diorite  bearing  a  little  musco- 


Fig.  40. — Sands  quarry,  Vinalhaven,  Maine,  showing  the  curvature 
of  the  sheets,  the  intersecting  joint  face  and  the  north  10°  east  chan- 
nelling along  the  cut-off.  By  courtesy  of  the  U.  S.  Geological  Survey. 

vite  and  biotite.  This  stone  is  of  fine,  even  texture.  It  also 
produces  a  norite  of  greenish-black  color  and  even  texture; 
a  mica-quartz  diorite  of  dark  gray  color;  a  dark  red  granite 
speckled  with  pale  green  shades ;  a  biotite  granite  of  bright 
pinkish  color.  The  red  granite  in  the  two  corner  wings  of 
the  American  Museum  of  Natural  History  in  New  York  is 
from  the  Redbeach  Granite  Company's  quarry  in  the  town  of 
Calais.  The  Maine  Red  Granite  Company  of  Calais  possesses 


GRANITES 


55 


the   most  extensive   plant   for   cutting  and   polishing  granite 
within  the  state. 

The  "  moose-a-bec  red  "  granite  of  Jonesport,  Hardwood 
Island,  consists  of  smoky  quartz,  reddish  orthoclase,  white 
oligoclase  and  black  biotite.  The  stone  is  of  coarse,  even- 
grained  texture.  It  is  used  in  the  lower  course  of  the  new 
building  of  the  College  of  Agriculture,  Syracuse  University. 

York  County 

In  York  County  the  Bennett  quarries  produce  a  quartz- 
mica  diorite  of  greenish,  dark  gray  color  and  even  texture. 


Fig.  41. — Round  Pond  black  granite  quarry,  Bristol,  Lincoln  County, 
Maine,  showing  the  quartz  diorite  sheets  crossed  by  a  2-foot  4-inch 
dike  of  coarse  pegmatite.  By  courtesy  of  the  U.  S.  Geological  Survey. 

The  Spence  and  Coombs  black  granite  is  a  gabbro  of  dark 
olive-brownish  color  and  ophitic  texture.  The  Ricker 
quarries  produce  a  biotite  granite  of  light  gray  color  and 
coarse  texture. 

Maryland. — The  chief  granite  quarries  in  Maryland  are 
situated  in  Baltimore  County,  and  the  product  is  known  as  the 
Woodstock  granite.  It  is  a  biotite  granite  of  light  gray  to 
dark  gray  color,  of  medium  texture  and  susceptible  of  a  fine 


,M>  BUILDING    STONES    AND    CLAVS 

polish.  A  considerable  amount  of  the  dark  gray  Baltimore 
gneiss  is  quarried  and  used  extensively  for  purposes  of  rough 
construction  in  the  city  of  Baltimore  and  vicinity.  (See  Figs. 
•['2  and  4lU 

Massachusetts. — In  considering  the  numerous  granites  of 
Massachusetts  only  those  quarries  will  be  described  that  have 
been  visited  by  the  author.  For  a  fuller  description  of  all  the 
granites  of  the  state  the  reader  is  referred  to  Bulletin  oO-i. 
V.  S.  Geological  Survey.  "The  Commercial  Granites  of  Massa- 
chusetts, New  Hampshire  and  Rhode  Island,"  by  T.  Nelson 
Dale. 


Fig.  4:2. — Granite  quarry  near  Woodstock,  Baltimore  Comity.  Mary- 
land.     By  courtesy   of  the   Maryland   Geological   Survey. 


Milford. — Milford  is  situated  in  Worcester  County  in  the 
eastern  half  of  the  state.  According  to  B.  K.  Emerson  and  T.  H. 
Perry  there  is  a  great  granite  area  of  a  constant  type  that 
extends  across  Massachusetts  and  Rhode  Island.  The  Milford 
granite  is  a  compact,  massive  rock,  somewhat  above  medium 
grain  and  of  light  color.  The  light  fresh  color  of  the  feldspar 
and  the  blue  of  the  quartz  give  it  in  some  places  a  slightly 
pinkish  tint.  It  is  now  much  used  as  a  structural  stone  under 
the  name  of  pink  granite.  It  is  a  biotite  granite.  There  are 


GRANITES 


57 


twelve  or  more  of  these  quarries  in  and  around  Milford.    (See 
Figs.  44  and  45.) 

Quincy. — The  Quincy  granite  area  falls  in  the  towns  of 
Quincy  and  Milton  in  Norfolk  County.  The  main  granitic 
mass  was  intruded  into  overlying  slates  which  in  places  have 
been  completely  eroded.  T.  Nelson  Dale  epitomizes  this 
granite  as  a  riebeckite-aegirite  granite.  Riebeckite  is  a  variety 
of  hornblende  which  occurs  in  crystals  longitudinally  striated 
and  with  perfect  prismatic  cleavage.  Aegirite  is  a  variety 
of  pyroxene  which  occurs  in  prismatic  forms  often  bluntly 
terminated  and  greenish  in  color.  Both  of  these  minerals 


Fig.  43. — McClenahan  granite  quarry,  Port  Deposit,  Cecil  County, 
Maryland,  showing  ideal  location  with  reference  to  railway  and  water 
transportation.  By  courtesy  of  the  Maryland  Geological  Survey. 

are  rich  in  sodium  and  iron.  The  granite  shades  from  a 
medium  gray  to  a  dark  purplish  gray  and  a  very  dark  bluish 
gray  color.  It  grades  from  a  medium  to  a  coarse  grain  and 
is  susceptible  of  a  fine  polish. 

This  high  polish  is  due  in  part  to  the  absence  of  mica  whose 
perfect  basal  cleavage  interferes  with  a  high  polish,  and  in 
its  place  as  a  ferromagnesian  mineral  the  varieties  of  horn- 
blende and  pyroxene  already  noted.  A  peculiar  variety  of 


58 


BUILDING    STONES   AND    CLAYS 


Fig.  44. — Polished   slab  of  pinkish  granite,   Milford,   Massachusetts. 
Photo,  by  C.  H.  Richardson. 


Fig.  45. — United  States  Post  Office,  New  York  City,  built  of  granite 
from  Milford,  Massachusetts.  By  courtesy  of  the  Webb  Pink  Granite 
Company,  Worcester,  Massachusetts. 


GRANITES 


59 


this  granite  is  commercially  known  as  the  "Gold  leaf."  The 
stone  is  of  medium  texture,  bluish  green  gray  color  with 
yellow  spots  that  are  caused  by  a  limonite  stain.  Quincy 
granite  is  one  of  the  most  popular  monumental  stones  in  the 
world.  It  is  used  also  for  constructional  work.  When 
fashioned  into  polished  pillars  or  colonnades  it  is  without  a 
peer  in  its  decorative  effect.  It  was  from  this  granite  that 
Bunker  Hill  monument  was  erected  in  1825.  (See  Figs.  46, 
47  and  48.) 


Fig.  46. — Ball  of  polished  Quincy  granite  from  the  Wigwam  quar- 
ries, Quincy,  Massachusetts.  Diameter  76  inches.  Weight  22,010 
pounds.  By  courtesy  of  the  U.  S.  Geological  Survey. 

Rockport.  —  The  Rockport  quarries  are  situated  on  the 
eastern  and  northern  part  of  Cape  Ann.  According  to  N.  S. 
Shaler  the  entire  cape  is  of  granite  traversed  here  and  there 
by  diabase  dikes  and  occasionally  by  quartz  porphyry  dikes. 
There  are  two  varieties  of  Rockport  granite.  One  is  a  horn- 


60 


BUILDING    STONES   AND    CLAYS 


blende  granite  of  medium  gray  color  and  spotted  with  black. 
It  is  of  medium  to  coarse  texture.  The  other  is  also  a  horn- 
blende granite.  It  is  of  dark  olive  gray  color,  spotted  with 
black  and  commercially  known  as  green  granite.  Two  other 
varieties  of  building  or  decorative  stone  are  quarried  on  a 
small  scale  on  Cape  Ann.  One  is  an  augite  syenite  and  the 
other  an  altered  diabase  porphyry.  (See  Figs.  49  and  50.) 


Fig.  47. — Dell  Hitchcock  granite  quarry,  North  Commons,  Quincy, 
Massachusetts,  from  the  west  side.  By  courtesy  of  the  U.  S.  Geo- 
logical Survey. 


Minnesota. — According  to  N.  H.  Winchell  more  than  half 
of  the  state  is  underlaid  by  that  series  of  crystalline  rocks 
to  which  granite  belongs.  In  the  northern  part  of  the  state 
there  are  many  outcrops  of  a  light  gray  granite  that  have 


GRANITES  61 

remained  unopened  on  account  of  the  absence  of  settlements 
and  the  difficulties  of  transportation. 

East  St.  Cloud. — These  quarries  were  opened  in  1868  and 
the  product  was  used  in  the  construction  of  the  Custom  House 
and  Post  Office  in  St.  Paul.  Two  types  of  stone  are  present. 
One  is  of  gray  color,  fine  and  close  texture.  The  other  is  a 
red  granite  of  much  coarser  grain.  The  ferromagnesian  min- 
erals present  are  hornblende  and  chlorite.  A  similar  granite 
to  the  red  variety  of  St.  Cloud  is  found  at  Watab  in  Benton 
County.  (See  Fig.  51.) 

Missouri. — Large  masses  of  granite  appear  in  Missouri  in 
Iron,  Madison  and  St.  Francois  Counties  but  none  of  them 
are  extensively  worked,  save  the  red  granite  of  Graniteville 


Fig.  48. — Polished  disc  of  light  Quincy  granite,  Quincy,  Massachu- 
setts. Photo,  by  C.  H.  Richardson. 

and  the  syenite  which  finds  its  way  into  the  St.  Louis  and 
Chicago  markets.  This  stone  admits  of  a  good  polish  and 
is  well  suited  for  monumental  work. 

Montana. — Lewis  and  Clarke  County  is  the  largest  pro- 
ducer of  granite  in  the  state.  This  county  furnishes  light 
gray  biotite  granites  and  coarse,  gray,  hornblende-mica 
granites.  Difficulties  in  transportation  enter  into  the  problem 
of  the  commercial  development  of  these  desirable  products. 

New  Hampshire. — The  granites  of  New  Hampshire  are 
widely  distributed  in  the  central  and  eastern  part  of  the 
State  with  a  few  less  important  quarries  of  granites  and 
gneisses  in  the  western  part.  The  author  has  examined  either 
outcrops  or  quarries  and  made  microscopic  sections  of  samples 


62  BUILDING    STONES    AND    CLAYS 

collected  in  Allentown,  Concord,  Conway,  Enfield,  Farming- 
ton,  Fitzwilliam,  Grafton,  Groton,  Hanover,  Hooksett,  Leb- 
anon, Manchester,  Milford,  Marlboro,  Pelham,  Salem,  Sun- 
japee  and  elsewhere.  Only  a  few  of  the  more  important 
granites  from  a  commercial  standpoint  can  be  described. 


li 


Fig.  49. — Deep  Pit  quarry  of  Rockport  Granite  Company,  near  Bay 
View  on  Cape  Ann,  Massachusetts,  looking  north.  By  courtesy  of 
the  U.  S.  Geological  Survey. 


Concord. — The  Concord  granite  is  according  to  G.  P.  Merrill 
one  of  the  most  important  granites  of  the  United  States.  It 
is  a  muscovite-biotite  granite  of  medium  gray  color  and  fine 
to  medium  texture.  It  ranks  fourth  among  the  white 
granites  of  America.  In  the  order  of  decreasing  whiteness 
the  list  is  Bethel,  Vermont;  North  Jay,  Maine;  Hallowell, 


GRANITES 


Fig.  50. — Post  Office,  Boston,  Massachusetts,  built  of  Rockport 
gray  granite.  Rockport,  Massachusetts.  By  courtesy  of  the  Rock- 
port  Granite  Company. 


Fig.    51. — Polished    disc    of    hornblende    granite. 
Minnesota.     Photo,  bv  C.  H.  Richardson. 


East    St.    Cloud, 


64 


BUILDING    STONES   AND    CLAYS 


mm 


^  o 
*o  ^ 

o  „ 
o^, 
—  '— 
O  O 

O- 


, 


sg 

'2  o 


GRANITES 


65 


Ic*^ 


Fig.  53. — Granite  quarry,  Concord,  New  Hampshire,  showing^  thick- 
ness of  sheets  and  work  of  the  channelling  machine.  Photo,  by  the 
Kimball  Photographic  Company,  Concord,  New  Hampshire. 


66 


BUILDING    STONES   AND    CLAYS 


Maine;  Concord,  New  Hampshire.  (The  author  has  in  his 
possession  a  five-inch  polished  disc  of  what  is  catalogued  by 
the  owners  of  the  stone  as  "A  New  Barre  Granite/  Concord, 
New  Hampshire.  This  disc  shows  a  rapid  deterioration  from 
the  oxidation  of  the  sulphur  and  iron  content.  The  presence 


Fig.  54. — Polished  cylinder  of  green  granite,  North  Conway,  New 
Hampshire.  Photo,  by  C.  H.  Richardson. 

of  sulphur  is  further  substantiated  by  an  analysis  of  a  sample 
of  Concord  granite  made  by  Sherman  and  Edwards  and 
collected  by  W.  O.  Crosby  wThich  showed  .27  per  cent,  sul- 
phur. (See  Figs.  52  and  53.) 

The  sample  cited  may,  however,  be  from  near  the  contact 
with  the  associated  gneisses  that  are  far  more  likely  to  carry 
accessory  pyrite.) 

Conway. — The  Conway  quarries  are  situated  near  North 
Conway  in  Carroll  County.  The  quarry  sites  are  upon  both 
the  east  and  west  sides  of  the  Saco  valley.  According  to  T. 
Nelson  Dale  the  geological  features  of  general  interest  in  the 
Conway  granites  are  their  marked  rift  and  grain,  the  rift  being 


GRANITES  67 

uniformly  horizontal  and  the  grain  vertical ;  the  contiguity 
of  a  yellowish  green  biotite-hornblende  granite  to  a  pink 
biotite  granite  at  Redstone.  These  two  granites  now  side 
by  side  represent  originally  different  materials.  The  feldspars 


Fig.  55. — Contact  of  granite  and  overlying  gneiss  at  the  Milford 
Granite  Company's  quarry,  Milford,  New  Hampshire,  looking  west. 
By  courtesy  of  the  U.  S.  Geological  Survey. 


of  one  are  tinted  by  the  limonitization  of  the  associated  allan- 
ite  and  hornblende  and  of  the  other  by  the  hematitization-  of 
magnetite  or  ferrite.  (See  Fig.  5-1.) 

Milford. — The  village  of  Milford  is  situated  on  the  Souhegan 
River.     The  most  of  the  quarries  lie  in  a  southerly  direction 


68 


BUILDING    STONES   AND    CLAYS 


some  four  miles  from  the  village.  This  granite  area  is  unique 
in  one  respect  for  it  represents  a  granitic  mass  now  overlaid 
by  a  granite  gneiss  that  was  once  a  granite  of  an  earlier 
period  of  intrusion,  and  subsequently  metamorphosed  into  a 
gneiss.  The  granites  are  quartz  monzonites  of  light,  medium, 
and  dark  gray  hues,  and  of  fine  even  texture  with  one  ex- 
ception. (See  Fig.  55.) 

Sunapec. — The  structural  and  ornamental  stones  of  the  area 
of  Lake  Sunapee  consist  of  a  biotite-muscovite  granite  which 
is  light  gray  in  color  and  of  fine  texture,  and  a  black  granite 
which  is  a  quartz-mica  diorite  of  dark  bluish  gray  color  and 
fine  texture.  The  last  stone  when  polished  appears  black, 


Fig.    56. — Pompton    pink    granite,    Pompton,    New    Jersey,    showing 
pegmatitic  characteristics.     By  courtesy  of  J.  Volney  Lewis. 

mottled  with  white,  and  is  largely  used  for  monumental  work. 
New  Jersey. — The  granitic  and  gneissoid  belt  of  rocks 
traverses  the  state  in  a  northeasterly  and  southwesterly  direc- 
tion. Only  a  few  quarries  appear  to  have  been  wrorked  to 
any  considerable  extent.  The  best  known  of  these  granites 
are  the  Pompton  pink  granite  which  is  coarse  grained ;  the 
Dover  light  gray  granite  which  is  gneissoid  ;  the  Cranberry 


GRANITES 


69 


Lake  white  granite  which  is  fine  grained  and  the  German 
Valley  granite  which  is  of  medium  texture.  (See  Figs.  56 
and  57.) 

New    York. — Although   the    state   of    New   York   contains   a 
vast   area  of  igneous  rocks  it  has   never  been  an  important 


Fig.  57. — St.  Paul's  church,  Paterson,  New  Jersey,  built  of  Pompton 
pink  granite.  By  courtesy  of  J.  Volney  Lewis. 

factor  in  the  granite  industry.  The  best  known  granite  of 
the  present  time  comes  from  the  Island  of  Picton  in  the  St. 
Lawrence  River.  It  is  a  fine  grained  pink  granite,  well 
adapted  to  structural  and  monumental  work.  It  dresses  well 
and  is  susceptible  of  a  fine  polish.  The  new  wing  of  the 
American  Museum  of  Natural  History  in  New  York  is  of 
this  stone.  (See  Fig.  58.) 

Grindstone  Island,  N.  Y.,  also  in  the  St.  Lawrence  River, 
furnishes  a  deep  red  coarsely  grained  crystalline  granite,  which 
is  susceptible  of  a  good  polish  and  is  used  for  monumental 
work.  It  is  a  hornblende  granite.  The  two  polished  columns 
in  the  Senate  Chamber  at  Albany  are  of  this  stone.  (See 
Fig.  59.) 

The  Keeseville  granite  which  is  some  five  miles  from  Ausable 
Chasm  in  the  Champlain  valley  is  a  norite.  It  contains  the 
feldspar  labradorite,  and  the  pyroxene,  hypersthene.  The 
hypersthene  sometimes  appears  as  black  knots  which  ulti- 
mately lead  to  a  discoloration  of  the  stone  due  to  the  oxida- 
tion of  the  iron  content  of  the  hypersthene.  Where  this 


70 


BUILDING    STONES   AND    CLAYS 


mineral  is  uniformly  distributed  throughout  the  rock  mass 
the  stone  takes  a  fine  polish  and  is  well  suited  for  decorative 
interior  work. 

North  Carolina. — According-  to  T.  L.  Watson  about  one- 
half  of  the  entire  area  of  the  state  is  covered  by  irruptives, 
although  the  granites  are  not  extensively  worked.  From  a 
mineralogical  standpoint  Watson  makes  the  following  classi- 
fication : 


Fig.  58.— Polished  block  of  red  Picton   granite  with  drove  margin, 
Picton  Island,   New  York.     Photo,   by  C.  H.   Richardson. 

1.  Biotite  granite,  with  or  without  muscovite,  and  including 
most  of  the  areas  .of  the  state,  such  as  Mount  Airy,  Dunns 
Mountain   and    Graystone. 

2.  Hornblende-biotite    granite,    including    the    granites    of 
northern  and  southern  Mecklenburg  County. 


GRANITES 


71 


3.  Muscovite  granite,   with  or  without  biotite,  as  Warren 
Plains  in  Warren  County. 

4.  Epidote  granite  from  Madison  County. 

Oklahoma. — The  Arbuckle  and  Wichita  Mountains  furnish 
a  few  granites  of  commercial  importance.  The  Arbuckle 
granite  is  pink  in  color  and  of  coarse  texture.  It  is  used  for 
structural  work.  The  Wichita  granite  varies  from  a  light 
pink  to  a  dark  red  color  and  ranges  from  a  fine  to  a  coarse 
texture. 

Pennsylvania.— Although  this  state  ranks  among  the  first 
in  production  of  building  stones,  it  appears  to  produce  little 
if  any  true  granite.  A  dark  hornblende  gneiss  has  been 
quarried  in  the  vicinity  of  Philadelphia  and  used  locally  for 
purposes  of  construction  since  the  days  of  William  Penn. 


Fig.  59. — Polished  slab  of  red  granite,  Grindstone  Island,  St.  Law- 
rence River,  New  York.  Photo,  by  C.  H.  Richardson. 

Gneiss   is   also    quarried   in    Chester,    Delaware    County,   and 
used  both  for  construction  and  foundation  work. 

Rhode  Island. — The  quarries  at  Westerly,  Rhode  Island,  are 
the  only  ones  in  the  state  visited  by  the  author.  The  geo- 
logical features  here  in  certain  respects  are  similar  to  those 
at  Milford,  New  Hampshire.  In  early  geological  times  an 
acid  intrusive  of  granitic  composition  invaded  the  terranes 
bordering  the  Atlantic  coast.  After  the  crystallization  of  this 
granite  it  was  subjected  to  compressive  stresses  sufficient  to 
crush,  elongate  and  re-arrange  the  minerals  of  the  earlier 
granite  into  a  gneiss.  The  gneiss  was  later  invaded  by  the 


72  BUILDING    STONES    AND    CLAYS 

present  granite  stock    from    which    the    fine    statuary    material 
is  now  derived.    (See  Fig.  60.) 

T.  Nelson  Dale  cites  the  following  order  of  geological  events 
transpiring  about  Westerly:  (1)  A  finely  banded  biotite 
gneiss  forms  the  surface.  (2)  Intrusion  by  the  red  granite 
of  the  hill  northwest  of  Westerly  and  by  the  gray  granite 
of  Niantic.  (3)  Metamorphism  of  the  red  and  gray  granite 


Fig.   60. — Job  monument  cut  from  Westerly,   Rhode  Island,  granite 
and  erected  in  Baltimore,  Maryland.     Photo,  by  C.  H.  Richardson. 

converting  it  about  Niantic  into  a  porphyritic  gneiss.  (4)  In- 
trusion of  the  Westerly  and  Niantic  fine  granites,  in  some 
places  into  the  earlier  banded  biotite  gneiss,  in  others  into 
the  more  or  less  altered  granite  gneiss.  (5)  Pegmatite  dikes 
traverse  both  the  Westerly  granites  and  the  Sterling  granite 
gneiss.  (6)  A  diabase  dike  traverses  alike  the  Westerly 
granite,  the  Sterling  granite  and  the  pegmatite  dikes. 


GRANITES  73 

Three  different  types  of  granite  are  pronounced  at  Westerly, 

(1)  The  Westerly  wThite  statuary  granite  is  a  quartz  monzonite 
of  pinkish  or  buff  medium  gray  color  and  fine  even  texture. 

(2)  The   blue   Westerly  granite   is   also   a   quartz   monzonite 
with   fine   black   particles   of  biotite,    medium   color   and   fine 
even  texture.    (3)  The  red  Westerly  granite  is  a  biotite  granite 
of  reddish  gray  color,  speckled  with  black,  and  varying  from 
medium  to  coarse  texture.    (See  Fig.  61.) 

South  Carolina. — The  chief  producing  granite  areas  of  the 
state  are  situated  in  Edgefield,  Fairfield,  Lancaster,  Lexing- 
ton, Pickens  and  Richland  Counties.  They  are  essentially 


Fig.  61. — Mausoleum  of  Russell  Sage,  cut  from  Westerly,  Rhode 
Island,  granite  and  erected  in  Oakwood  Cemetery,  Troy,  New  York. 
H.  Q.  French,  architect.  By  courtesy  of  E.  L.  French. 

biotite  granites  and  range  in  color  from  light  to  dark  gray 
and  in  texture  from  fine  to  coarsely  porphyritic. 

Tennessee. — The  granites  of  this  state  are  found  in  Carter, 
Cooke,  Johnson,  Polk  and  Washington  Counties.  Some  of 
these  are  used  locally  for  structural  work  and  some  for  monu- 
mental work. 

Texas.  —  This  state  produces  biotite  granites  in  Burnet 
County.  They  are  red  granites  varying  in  texture  from  fine 
to  coarse.  Also  from  Gillespie  County  both  red  and  gray 
granites.  (See  Figs.  62  and  63.) 


74 


BUILDING    STONES   AND    CLAYS 


Utah. — The  best  representative  of  the  Utah  granites  is 
found  in  the  Mormon  Temple  at  Salt  Lake  City.  It  came  from 
the  light  gray  granite  area  in  Little  Cottonwood  Canon. 

Vermont. — The  author  has  spent  some  part  of  twenty-two 
consecutive  summers  in  detailed  work  on  the  Vermont  Geo- 
logical Survey  and  visited  more  than  one  hundred  granite 
quarries,  prospects  and  outcrops,  many  of  which  have  been 
briefly  described  in  the  Biennial  Reports  of  the  State  Geolo- 
gist. It  is  impossible  in  this  brief  work  to  describe  them  all. 
Only  the  more  important  areas  will  be  mentioned.  The 
granites  vary  widely  in  color,  texture,  and  in  mineral  compo- 
sition. The  granite  lies  between  the  Connecticut  River  on 


Fig.    (>:>. — Red    granite    quarry,    Granite    Mountain,    Btirnet    County, 
Texas.      By   courtesy  of   W.   B.   Phillips. 

the  east  and  the  main  axis  of  the  Green  Mountains  on  the 
west.  Every  county  in  the  eastern  half  of  the  state  carries 
granite.  The  granites  were  intruded  not  only  into  the  Waits 
River  limestones  and  associated  phyllite  schists  of  Ordovi- 
cian  age,  but  also  into  the  Cambrian  metamorphics  that  flank 
them  upon  both  the  east  and  the  west.  The  intrusives  often 
appear  as  the  upper  portions  of  a  great  batholith.  One 
peculiar  and  interesting  feature  of  these  granites  is  the  large 
inclusions  of  the  intruded  rocks,  sometimes  more  than  fifty 
feet  in  diameter.  The  most  of  the  granites,  if  not  all,  were 


GRANITES  75 

introduced  with  the  Devonian  revolution  for  they  appear  in 
Canada  cutting  distinctly  Devonian  strata.  Some  of  them, 
however,  may  be  as  late  as  the  Carboniferous,  and  the  asso- 
ciated diabase  dikes  and  stocks  so  pronounced  in  the  northern 
part  of  the  state  as  late  as  theTriassic.  There  was,  however, 
an  earlier  period  of  granitic  intrusion  into  the  Cambrian 
terranes  for  boulders  of  granite  are  found  in  the  Irasburg 
conglomerate  which  forms  the  base  of  the  Ordovician  series. 
The  granites  of  Vermont  appear  in  seven  of  the  fourteen 
counties  of  the  state,  viz :  Caledonia,  Essex,  Orange,  Orleans, 
Washington,  Windham  and  Windsor.  The  granite  deposits 
of  the  towns  in  each  county  will  be  considered  in  alphabetic 
order,  regardless  of  the  commercial  significance  of  the  rock. 


Fig.  63. — State  Capitol,  Austin,  Texas,  built  of  red  granite  from 
Granite  Mountain,  Texas.  Photo,  furnished  by  D.  J.  Jones. 

Caledonia  County 

Groton. — The  Groton  granite  is  a  quartz  monzonite  which 
is  quite  extensively  advertised  as  the  "  Vermont  blue  granite." 
In  color  it  is  decidedly  bluish  gray  which  fact  is  responsible 
for  its  commercial  name.  In  texture  it  varies  from  fine  to 
medium.  The  stone  takes  a  good  polish  and  is  used  largely 
for  monumental  work.  (See  Fig.  64.) 

Hardwick. — The  town  of  Hardwick  has  furnished  three 
different  grades  of  granite  for  monumental  work.  (1)  A  fine 
light  gray  granite  bearing  but  little  biotite,  from  which  more 


76  BUILDING    STONES    AND    CLAYS 

than  fifty  statuettes  have  been  carved.  (2)  A  medium  gray  to 
dark  quartz  monzonite  from  the  Mackville  quarries.  (3)  A 
quartz  monzonite  from  Buffalo  Hill.  This  stone  is  named 
"  dark  blue  Hardwick."  It  is  darker  than  the  highly  prized 
dark  Barre  granite  and  lighter  than  the  darkest  of  the  Quincy 
granite.  Its  rich  color  is  clue  in  part  to  the  smoky  quartz 
and  in  part  to  the  presence  of  much  biotite  uniformly  scattered 
throughout  the  stone:  perhaps  in  part  also  to  the  paucity 
of  the  white  mica,  or  muscovite.  The  stone  receives  a  fine 
polish  and  in  texture  it  is  medium. 


Fig.  64.— Granite  quarry,  Groton,  Vermont,  showing  thickness  of 
sheets.  Photo,  by  C.  H.  Richardson. 

Kirby—The  Grout  quarries  are  situated  on  the  south  side 
of  Kirby  Mountain.  The  stone  is  a  light  to  medium  biotite 
granite,  of  fine  even  texture,  and  has  been  sold  under  the 
name  of  "light  Barre  granite"  which  it  somewhat  closely 
resembles.  The  stone  is  very  bright  in  color.  The  fine  mica 
crystals  throughout  the  stone,  together  with  the  light  colored 
quartz,  prevent  strong  contrasts. 


GRANITES 


77 


The  Burke  quarries  and  the  Kearney  Hill  quarries  are 
situated  on  the  west  foot  of  Kirby  Mountain.  They  both 
represent  quartz  monzonites  which  shade  from  light  to 
medium  gray  in  color,  and  from  fine  to  coarse  texture.  The 
latter  quarries  yield  the  coarser  stone  of  the  two  products. 
(See  Fig.  65.) 

Nezvark. — The  town  of  Newark  is  capable  of  producing  a 
granite  that  is  quite  unlike  in  color  'any  other  stone  in  the 
state.  The  stone  is  a  biotite  granite  shading  from  a  light 
pink  to  a  red  color.  It  is  commercially  called  "  Newark  pink 
granite."  It  is  of  rather  coarse  texture.  The  stone  is  sus- 
ceptible of  a  good  polish  and  well  suited  for  monumental 


Fig.  65. — Granite  quarry,  Kirby  Mountain,  Vermont,  showing  thick- 
ness and  dip  of  sheets.     Photo,  by  C.  H.  Richardson. 


or  decorative  work.  The  author  collected  samples  from 
Newark  before  the  quarries  were  opened  and  had  the  samples 
polished.  It  appears  equal  in  decorative  effect  with  the  kin- 
dred granites  of  Maine  and  Scotland.  (See  Fig.  66.) 

Ryegate. — The  Ryegate  quarries  are  situated  on  the  south- 
west and  northeast  slopes  of  Blue  Mountain.  The  former 
are  quartz  monzonites  and  the  latter  a  biotite  granite.  They 
vary  in  color  from  light  to  medium  and  in  texture  from  fine 
to  medium.  They  are  used  for  monumental  and  structural 
work.  (See  Fig.  67.) 


78  BUILDING    STONES   AND    CLAYS 

Essex  County 

According  to  C.  H.  Hitchcock  nearly  all  of  this  county  is 
underlaid  by  granite.  Some  stone  has  been  blasted  for 
foundation  work  but  no  quarries  have  to  the  present  time 
been  systematically  worked.  Later  reconnaissance  work  has 
proven  the  rocks  to  be  metamorphosed  sedimentaries  with 
some  granitic  intrusives. 

Orange  County 

Chelsea. — Where  the  towns  of  Chelsea,  Strafford,  Tun- 
bridge  and  Vershire  meet  in  a  common  corner  there  appears 
a  granite  outcrop  which  has  been  worked  to  some  extent  for 
monumental  purposes.  The  stone  is  of  a  light  gray  color 
and  of  medium  texture.  Distance  from  railroads  is  the  chief 
difficulty  in  its  development. 


Fig.  66. — Polished  sample  of  red  granite,  Newark,  Vermont.  Photo, 
by  C.  H.  Richardson. 

Randolph. — The  granite  of  Randolph  is  a  quartz  monzonite. 
It  stands  next  to  the  Bethel  in  whiteness  amongst  all  the 
granites  of  the  state.  Biotite  which  characterizes  most  of  the 
granites  of  the  state  is  wanting.  Muscovite,  the  white  mica, 
is  present  only  in  small  proportion,  2.3  per  cent.  The  stone 
is  of  fine  even  texture,  hammers  white,  receives  a  high  polish 
and  is  well  suited  for  monumental  and  structural  wrork. 

Topsham. — There  are  numerous  small  outcrops  of  granite 
in  Topsham  and  some  of  these  have  been  worked  locally  for 
underpinning  and  monumental  purposes.  Two  localities  only 


GRANITES  79 

are  extensively  operated.  One  of  these  is  near  the  village  of 
South  Ryegate  in  Caledonia  County  and  the  other  is  on  Pine 
Mountain.  The  granites  are  quartz  monzonites  of  bluish  gray 
color  and  medium  texture.  (See  Fig.  68.) 

Williamstozvn.—The   Williamstown   granites   belong   to   the 
same  great  mass  as  the  Barre  granites  in  Washington  County. 


Fig.  67. — Granite  quarry,  Blue  Mountain,  Ryegate,  Vermont.  Photo 
by  C.  H.  Richardson. 

They  are  of  dark  gray  color  and  of  fine  to  medium  texture. 
They  are  sold  under  the  names  of  "  dark  Barre  "  and  "  dark 
blue  granite." 

Orleans  County 
Craftsbury. — An    orbicular   granite    occurs    in    the    village    of 


80 


BUILDING    STONES   AND    CLAYS 


Craftsbury  and  immediately  to  the  east  of  the  village.  This 
granite  is  sufficiently  peculiar  to  merit  more  than  a  passing 
notice.  It  was  described  by  C.  H.  Hitchcock  and  A.  D.  Hager 
in  their  Report  on  the  Geology  of  Vermont,  Vol.  II,  1861, 
as  a  concretionary  granite  and  as  Craftsbury  pudding  granite. 
It  was  also  described  bv  G.  Hawes  in  1878  and  by  K.  Chrus- 


pjg    68. — Polished  slab  of  Waits  River  granite,  Topsham,  Vermont. 
Photo,   by  C.   H.   Richardson. 


Fig.    69. — Orbicular    granite,    Craftsbury,    Vermont,     showing    con- 
centric arrangement  of  orbules.     Photo,  by  C.   H.  Richardson. 

thov  in  1878  and  1894.  Also  by  T.  N.  Dale  in  Bull.  275,  U.  S. 
Geological  Survey,  1906.  It  was  photographed  and  briefly 
described  by  C.  H.  Richardson  in  the  Report  of  the  Vermont 
State  Geologist  of  1905-1006  and  also  in  the  Report  of  1911-1912 


GRANITES 


81 


by  the  same  author.  Orbicular  granites  are  also  found  in  Stan- 
stead,  Quebec,  and  in  Bethel,  Newfane  and  Northneld,  Ver- 
mont, but  in  these  localities  the  orbicular  structure  is  not  so 
pronouncedly  developed.  In  the  Bethel  granite  the  discoid 
torms  lie  in  sheets  parallel  to  the  flow  structure  of  the  outer 
portions  of  the  granite  mass,  and  the  major  axes  of  the  discs 
are  parallel  to  the  micaceous  flowage  bands.  B.  Frosterus 
applies  the  principle  to  the  orbicular  granites  of  Finland,  and 
T.  N.  Dale  to  those  of  Bethel,  that  the  nodules  are  basic 
segregations  lying  in  a  more  basic  part  of  the  granite,  in- 


^•IMMMBHM^^HHHM^^^H^MM^^^^MHHBHM 

Fig.  70. — Orbicular  granite,  Craftsbury,  Vermont,  showing  rift 
and  arrangement  of  orbules.  Photo,  by  C.  H.  Richardson. 

dicating  that  the  orbicular  structure  is  simply  a  basic  flowage 
and  that  the  nodules  themselves  lie  in  this  as  still  more  basic 
segregations.  (See  Fig.  69.) 

The  nodules  in  the  Craftsbury  granite  consist  mainly  of 
convex  scales  of  biotite  with  some  quartz  granules  and  feld- 
spathic  particles.  The  convolutions  and  elongations  of  the 
discoid  particles  suggest  the  existence  of  a  strain  after  segre- 
gation was  complete.  They  are  scattered  with  a  fair  degree 
of  uniformity  throughout  the  entire  granite  stock,  differing 

6 


82  BUILDING    STONES   AND    CLAYS 

in  this  respect  from  the  other  areas  cited  a^ove.  A  cubic 
block  of  this  granite  in  the  museum  at  Syracuse  University 
shows  the  nodules  to  be  arranged  in  a  somewhat  orbital 
manner,  the  outer  circles  increasing  constantly  in  diameter. 
This  assemblage  of  black  nodules  in  the  gray  mass  of  the 
granite  suggests  a  basic  segregation  of  the  most  basic  material 
in  a  magm.a  more  basic  than  that  which  represents  today  the 
normal  biotite  granites  of  the  state.  The  visible  outcrop  may 
represent  only  the  peripheral  portions  of  the  granite  stock 
and,  if  so,  the  nodules  themselves  lie  in  the  zone  of  flowage. 
The  quarries  have  never  been  opened  beneath  the  surface 
because  the  nodules  preclude  a  high  polish  of  the  stone,  and 


Fig.  71. — Granite  quarry,  Newport,  Vermont,  showing  thickness  and 
curvature  of  sheets.     Photo,  by  C.   H.   Richardson. 


its  use  for  structural  work.  It  has  been  used  to  a  consider- 
able extent  for  cellar  walls,  underpinnings,  abutments  of 
bridges  and  guards.  The  stone  possesses  good  rift  and  grain. 
(See  Fig.  70.) 

Derby. — Three  different  types  of  granite  are  quarried  in 
the  township.  (1)  A  quartz  monzonite  bearing  both  mus- 
covite  and  biotite.  The  stone  is  of  bluish  gray  color  and 
varies  from  fine  to  medium  texture.  The  stone  grades  be- 
tween the  lightest  of  the  Barre  granites  and  those  of  Hallo- 
well,  Maine.  This  granite  is  easily  worked,  and  is  well  suited 


GRANITES 


83 


for    both    monumental    and    constructional    purposes.      (See 
Fig.  71.) 

(2)  The  granite  near  Beebe  Plains  is  a  very  light  gray  color 
and  of  even  medium  texture.  It  is  however  darker  than  the 
Bethel  stone.  It  bears  biotite  uniformly  distributed  through- 
out the  stone. 


Fig.  72. — Jones  Brothers  granite  quarry,  Barre,  Vermont,  showing 
excavations  over  300  feet  in  length.  Photo,  by  C.  H.  Richardson. 

(3)  The  third  type  is  found  on  the  line  of  the  International 
Boundary  between  Vermont  and  Canada.  It  is  only  a  short 
distance  south  of  the  Graniteville,  Quebec,  quarries.  The 
stone  is  in  part  a  very  dark  stone  almost  equal  to  the  black 
granites  of  Maine.  It  is  rich  in  biotite  and  represents  a  segre- 
gation of  the  more  basic  product  of  the  main  magma. 


84  BUILDING    STONES    AND    CLAYS 

Irasburg. — At  the  eastern  base  of  the  Lowell  Mountain  in 
Irasburg  there  is  a  light  gray  biotite  granite  of  fine  and  even 
texture.  It  possesses  perfect  rift  and  grain.  Blocks  of  any 
dimension  desired  can  be  obtained.  It  takes  a  good  polish 
and  is  well  suited  for  structural  purposes. 


Fig.  73. — A  derrick  inverted  by  the  removal  of  the  granite  too  close 
to  a  steep  wall  of  mica  schist,  Barre,  Vermont.  Photo,  by  C.  H.  Rich- 
ardson. 

Washington  County 

Barre. — The  granite  industry  which  has  made  the  city  of 
Barre  possible  is  centered  at  Websterville  and  Graniteville 
about  ten  miles  to  the  southeast  of  Montpelier,  the  Capital 
of  the  State.  The  Harrington  quarries  were  opened  in  1837 
to  provide  the  stone  for  the  construction  of  the  Capitol  build- 


GRANITES 


85 


ing.  The  statement  was  then  made  that  "  This  is  the  last 
structure  that  will  ever  be  made  of  Barre  granite,  and  the 
last  load  that  wrill  ever  be  drawn  from  Harrington  Hill." 
The  fame  of  the  granite  is  now  world-wide  and  the  annual 
production  from  Harrington  Hill  surpasses  $1,000,000.  This 
hill  is  the  present  site  of  Graniteville. 


Fig.  74. — Jones  Brothers  quarry,  Barre,  Vermont,  showing  contact 
of  granite  with  phyllite  schist.  Photo,  by  C.  H.  Richardson. 

The  Barre  granites  are  known  commercially  under  the 
following  names :  "  white  Barre,"  "  light  Barre,"  "  medium 
Barre,"  "  dark  Barre  "  and  "  very  dark  Barre."  These  names 
are  all  based  upon  the  prevailing  colors  o£  the  quarry  pro- 
ducts. The  Barre  granites  grade  in  texture  from  fine  through 
medium  to  coarse.  They  are  all  true  biotite  granites  with  a 


86 


BUILDING    STONES   AND    CLAYS 


paucity  of  muscovite  wherever  the  white  mica  is  present. 
The  quarries  are  far  too  numerous  and  too  much  alike  to 
mention  in  detail.  The  quarries  show  a  sheeted  structure 
save  the  Innes  and  Cruikshank  quarry  at  Websterville  which 
represents  a  boulder  quarry.  The  granites  are  monumental, 
inscriptional,  decorative  and  constructional.  It  is  doubtful  if 


Jl 


Fig.  75. — Wetmore  and  Morse  granite  quarry,  Barre,  Vermont, 
showing  sheeted  structure.  Photo,  by  C.  H.  Richardson. 

any  granite  in  America  is  more  widely  known  than  the  Barre 
granite.    (See  Figs.  72,  73,  7-±,  75,  76,  77,  78  and  79.) 

Cabot. — The  granite  of  Cabot  is  a  quartz  monzonite  of  dark 
bluish  gray  color,  as  dark  as  the  darkest  of  the  Barre  granites. 
It  is  of  fine  even  structure  and  takes  a  good  polish.  The  clear 
quartz  and  black  mica  give  the  stone  a  strong  mineral 
contrast. 


GRANITES 


87 


Calais. — The  granites  of  Calais  are  biotite  granites  of  light 
to  medium  gray  color  and  of  fine  to  medium  texture.  The 
product  is  used  largely  for  monumental  work.  (See  Fig.  80.) 

Woodbury. — The,  granites  of  Woodbury  where  quarried, 
with  the  exception  of  that  of  Nichols  Ledge,  are  either  on 
Robeson  Mountain  or  in  its  immediate  vicinity.  They  occupy 


Fig.  76. — Wetmore  and  Morse  granite  quarry,  Barre,  Vermont, 
showing  head  seam  back  of  which  there  is  much  good  granite.  Photo, 
by  C.  H.  Richardson. 

a  somewhat  irregular  area  with  a  diameter  of  about  four 
miles.  Granite  masses  however  appear  upon  the  west  side  of 
the  valley  that  separates  Robeson  Mountain  from  Woodbury 
Mountain  but  these  are  not  quarried  to  any  considerable 
extent.  The  Woodbury  granites  proper  are  all  biotite  gran- 


88 


BUILDING    STONES   AND    CLAYS 


ites.  They  shade  in  color  from  white,  or  light  cream  color, 
through  medium  gray  to  a  dark  gray.  They  possess  even 
medium  texture. 

The  Fletcher  quarries  are  on  the  southeast  and  southwest 
sides  of  Robeson  Mountain.  One  set  of  sheets  varies  from 
one  to  five  feet  in  thickness  and  another  set  varies  from  five 
to  nine  feet  in  thickness.  T.  Nelson  Dale  states  in  the  Report 
of  the  Vermont  State  Geologist,  1909-1910,  "  In  300  granite 
quarries  visited  thus  far  by  the  writer  this  is  the  first  case  of 
double-sheet  structure  or  horizontal  jointing  observed."  Dale 
explains  this  peculiarity  by  the  existence  at  some  time  of  a 


Fig.  77. — Entrance  to  postofficc,  Barrc,  Vermont,  built  of  light  gray 
Barrc  granite.  Photo,  by  C.  H.  Richardson. 

secondary  compressive  strain  operating  differently  from  that 
which  produced  the  primary  sheet  structure  to  which  Robeson 
Mountain  owes  its  form.  (See  Figs.  81  and  82.) 

The  late  George  H.  Bickford,  President  of  the  Woodbury 
Granite  Company,  classified  their  granites  as  "  Vermont 
white,"  "  Imperial  blue,"  and  "  Woodbury  gray."  The  Wood- 
bury  white  granite  is  a  very  light,  slightly  buff  or  cream-tinted 
stone.  Its  quartz  is  of  pale  hue  and  there  is  a  paucity  of  the 
black  mica,  biotite.  This  gives  the  stone  a  strong  mineral 
contrast. 


GRANITES 


89 


The  Woodbury  gray  and  the  Woodbury  fine  dark  gray  granites 
are  on  the  east  to  northeast  sides  of  Robeson  Mountain  and 
are  of  fine  even  texture.  The  sheets  sometimes  reach  a 
thickness  of  forty  feet.  It  is  doubtful  if  larger  blocks  can" 
be  quarried  from  any  stone  in  America  than  can  be  obtained 
at  these  quarries,  or  that  any  company  has  facilities  for 
handling  larger  blocks  than  the  Woodbury  Granite  Company. 
The  Imperial  blue  quarries  are  located  near  Buck  Lake  and 


Fig.    78. — Monument    cut    from    Barrc    granite    and    erected    in    the 
cemetery  at  Hardwick,  Vermont.     Photo,  by  C.  H.  Richardson. 

are  called  the  Buck  Lake  quarries.  The  stone  is  of  dark 
bluish  gray  color  and  of  fine  even  texture.  The  Carnegie 
library,  Syracuse,  N.  Y.,  contains  the  Woodbury  gray  granite. 
The  Nichols  ledge  granite  is  from  light  to  bluish  gray  color 
and  of  very  fine  texture.  Distance  from  the  railroad  militates 
against  a  large  development  of  these  quarries.  (See  Figs.  83, 
84,  85,  86,  87,  88,  89,  90,  91,  92,  93  and  94.) 


90 


BUILDING    STONES   AND    CLAYS 


Windham  County 

Dummerston.  -  The  commercial  granites  of  Windham 
County  are  situated  on  the  northeast,  south  and  southwest 
sides  of  Black  Mountain.  They  are  all  quartz  monzonites. 
The  West  Dummerston  white  granite  bears  both  muscovite 
and  biotite  and  is  of  medium  texture.  The  product  is  used 
for  monumental  work,  structural  and  paving  blocks.  The 
quarries  on  the  south  and  northwest  sides  of  Black  Moun- 
tain produce  granites  of  darker  hue  and  finer  texture  than 
those  on  the  southwest  side  of  the  mountain.  (See  Fig.  95.} 


Fig.  79. — Monument  cut  by  Redmond  and  Hartigan  from  Barre 
granite,  Barre,  Vermont.  By  courtesy  of  Redmond  and  Hartigan. 

Windsor  Count}! 

Bethel. — The  Bethel  granite  is  situated  on  Christian  Hill 
about  three  miles  north  of  the  village  of  Bethel.  The  quar- 
ries of  the  Ellis  Brothers  are  on  the  east  side  of  the  hill  and 
those  of  the  Woodbury  Granite  Company  on  the  east  side 
and  top  of  the  hill.  The  granite  is  a  quartz  monzonite,  in 
texture  varying  from  fine  to  coarse.  It  surpasses  all  other 


GRANITES 


91 


known  granites  in  its  peculiar  whiteness.  The  author  has 
compared  freshly  dressed  blocks  of  this  stone  with  the  in- 
terior of  a  building  painted  with  white  lead  and  found  the 
granite  the  whiter  of  the  two.  Its  whiteness  is  due  to  the 
presence  of  clear  colorless  quartz,  white  oligoclase,  clear 
orthoclase,  white  muscovite  and  a  paucity  of  the  black  mica, 
biotite.  Many  of  the  polished  discs  appear  to  contain  no 
visible  biotite.  The  granite  is  hard,  cuts  to  a  perfect  edge 
and  is  one  of  the  best  constructional  stones  in  America.  It 
occurs  in  sheets  varying  in  thickness  from  five  to  twelve 


Fig.  80. — The  Patch  Company  granite  quarry,  Calais,  Vermont, 
showing  thickness  and  steep  dip  of  sheets.  Photo,  by  C.  H.  Rich- 
ardson. 

feet.  The  stone  has  a  remarkable  compression  test.  As  de- 
termined by  the  United  States  Arsenal  at  Watertown,  Mass., 
it  is  33,153  Ib.  to  the  cubic  inch.  (See  Figs.  96,  97,  98,  99  and 
100.) 

Windsor. — The  granites  quarried  in  Windsor  are  situated 
on  the  north  and  west  sides  of  Mount  Ascutney.  The  alti- 
tude of  the  mountain  as  given  by  the  average  of  21  different 
observations  made  by  the  author  is  3,320  feet.  It  rises  more 


92  BUILDING    STONES    AND    CLAYS 

than  3,000  feet  above  the  Connecticut  River,  and  2,999  feet 
above  Windsor.  The  granite  mass  was  intruded  into  the 
limestones  and  slates  of  Ordovician  age.  The  present,  isolated, 


Fig.  81. — A  6-foot  sheet  of  granite  in  the  E.  R.  Fletcher  quarry, 
Wooclbury,  Vermont,  showing  the  work  of  the  channelling  machine. 
Photo,  by  C.  H.  Richardson. 


Fig.    82. — E.    R.    Fletcher    granite,    Woodbnry,    Vermont,    showing 
polished   and   hammered    surface.      By   courtesy   of   E.    R.    Fletcher. 

conical  peak,  Mount  Ascutney,  may  be  taken  as  a  measuring 
rod   of    the    amount   of   denudation    that   has    taken    place    in 


GRANITES 


93 


Vermont  since  the  intrusion  of  the  various  granites.  With 
this  mountain  as  a  measuring  rod  the  amount  of  erosion  could 
not  have  been  less  than  3,000  feet.  It  probably  was  consider- 
ably greater  than  the  above  figure.  The  granite  of  Ascutney 
has  been  described  by  R.  A.  Daly,  Bulletin  209,  U.  S.  Geo- 
logical Survey,  1903.  Daly  classifies  the  stone  as  a  nord- 
markite.  It  was  earlier  classified  by  C.  H.  Hitchcock  as  a 


Fig.  83. — Quarry  of  the  Woodbury  Granite  Company  on  Robeson 
Mountain,  Woodbury,  Vermont,  showing  thickness  of  granite  sheets. 
Photo,  by  C.  H.  Richardson. 

syenite.  It  is  a  hornblende-augite  granite.  Its  mineral  com- 
position as  given  by  T.  Nelson  Dale  in  descending  order 
is  dark  olive  green  orthoclase,  interwoven  with  oligoclase 
with  cleavage  planes  stained  with  limonite ;  dark  smoky 


94  BUILDING    STONES   AND    CLAYS 

quartz  with  cracks  stained  with  limonite ;  green  hornblende ; 
augite ;  biotite  present  in  only  one  of  the  four  slides  examined. 
The  accessory  minerals  are  titanite,  magnetite,  or  ilmenite, 
zircon,  apatite  and  allanite.  The  secondary  minerals  are 
limonite  and  a  white  mica. 

The  stone  changes  from  a  dark  bluish  gray  color  when 
freshly  quarried  to  a  green  color  upon  exposure  to  the  atmos- 
phere. This  change  of  color  is  due  to  the  oxidation  of  ex- 
tremely minute  blackish  granules  of  ferrous  oxide  in  the 
feldspars,  and  to  the  combination  of  yellowish  brown  color 
from  the  limonite  thus  produced  with  the  bluish  gray  color 
of  the  unaltered  feldspars.  A  part  of  this  limonite  is  undoubt- 
edly due  to  the  oxidation  of  the  iron  content  of  the  accessory 
allanite. 


Fig.  84. — Polished  disc  of  Woodbury  gray  granite  from  quarry 
shown  in  Fig.  83.  Photo,  by  C.  H.  Richardson. 

This  granite  is  best  suited  for  dies,  monumental,  inscrip- 
tional,  wainscoting  and  columnar  work.  In  the  absence  of 
the  common  micas  the  stone  takes  a  very  high  polish  and 
the  polished  surface  of  the  raised  letters  stands  out  in  striking 
contrast  with  the  hammered  surfaces.  The  sixteen  polished 
columns  of  the  Library  of  Columbia  University,  New  York, 
are  of  this  stone.  (See  Fig.  101.) 

Virginia. — The  granites  of  Virginia  are  found  chiefly  in 
three  districts,  Fredericksburg,  Petersburg  and  Richmond 
areas.  The  first  area  furnishes  a  muscovite  granite  that  is 


GRANITES 


95 


very  light  gray  in  color  and  of  medium  texture ;  also  a  biotite 
granite  of  dark  bluish  gray  color  and  fine  texture.  The  second 
area  produces  a  biotite  granite  of  light  to  dark  gray  color 
and  of  fine  and  medium  texture ;  also  an  exceptionally  beau- 
tiful porphyritic  granite  from  near  Midlothian.  The  third 
area  furnishes  a  biotite  granite  of  gray  color  and  medium 
texture. 


Fig.  85. — Granite  quarry  of  the  Woodbury  Granite  Company,  near 
north  end  of  Robeson  Mountain,  Woodbury,  Vermont,  showing  thick- 
ness and  dip  of  sheets.  Photo,  by  C.  H.  Richardson. 

Wisconsin.  —  According  to  T.  C.  Chamberlin  the  great 
Laurentian  area  of  the  northern  portion  of  Wisconsin  is 
covered  with  granites  and  gneisses.  Quarries  are  operated 
in  Marathon  and  Marquette  Counties  and  furnish  fine  granites 
of  pink  color  and  even  texture. 


96  BUILDING    STONES   AND    CLAYS 

Wyoming. — Near  the  highest  point  of  the  Northern  Pacific 
Railroad  at  Sherman  there  is  a  large  body  of  coarse  red  gran- 
ite that  is  quite  similar  to  the  Scotch  granite,  so  largely  im- 
ported into  this  country  for  monumental  work. 

FOREIGN  GRANITES 

British  Columbia. — Granites  are  quarried  on  Jarvis  Inlet 
and  Burrard  Inlet  and  the  product  is  largely  consumed  in 
the  vicinity  of  Vancouver. 

New  Brunswick. — In  Kings  County  there  is  a  red  horn- 
blende granite  that  is  brought  into  the  New  England  States 
for  monumental  purposes  under  the  name  of  "Bay  of  Fundy 
granite."  It  can  be  easily  distinguished  from  the  red  granites 


Fig.  86. — Polished  slab  of  Vermont  white  granite,  Robeson  Moun- 
tain, Woodbury,  Vermont.  Photo,  by  C.  H.  Richardson. 

of  New  England  because  its  ferromagnesian  mineral  is  horn- 
blende instead  of  biotite  or  muscovite.  It  is  susceptible  of 
a  high  polish  on  account  of  the  absence  of  the  highly  cleav- 
able  micas. 

Nova  Scotia. — Gray  biotite  granites  are  quarried  at  Shel- 
burne  and  Purcell's  Cove  in  Halifax  County  and  imported 
to  some  extent  into  the  United  States.  These  vary  in  texture 
from  fine  to  coarse. 

Ontario. — One  of  the  best  granites  of  Ontario  is  that  found 
at  Kingston.  It  is  a  red  granite  of  fine  and  even  texture  well 
suited  for  monumental  and  decorative  interior  wrork. 

Quebec. — Quartz  monzonites,  biotite  granites  and  horn- 
blende granites  are  extremely  abundant  in  the  Province  of 
Quebec.  The  author  has  visited  scores  of  fine  quarries  in 


GRANITES 


97 


this  Province.  They  duplicate  the  Vermont  product  in  all 
lespects  save  the  white  granite  of  Bethel  and  the  green 
granite  of  Mount  Ascutney. 

England. — The  most  important  granitic  intrusions  in  Eng- 
land which  yield  stone  for  structural  purposes  are  located  in 


>"• 

'.* 


Fig.  87. — Imperial  blue  granite  quarry,  Buck  Lake  district,  Wood- 
bury,   Vermont,   showing  head  seams.     Photo,  by   C.  H.   Richardson. 

Cornwall  and  Devonshire.  According  to  J.  Watson  this  belt 
extends  in  the  form  of  a  broken  chain  from  Dartmoor  to  the 
Scilly  Islands.  The  stone  has  been  quarried  for  many  cen- 
turies. The  ancient  cromlechs,  monoliths,  Celtic  crosses  and 

7 


98  BUILDING    STONES   AND    CLAYS 

hut  dwellings  scattered  over  England  were  made  of  granite. 
The  granites  are  mostly  muscovite-biotite  granites  varying 
in  color  from  light  to  dark  gray  and  in  texture  from  fine  to 
coarse.  Where  porphyritic  the  phenocrysts  of  feldspar  are 
called  by  the  quarry  men  "  Horses'  Teeth."  (See  Fig.  102.) 

Ireland. — The  principal  granite  producing  counties  of  Ire- 
land are  Dublin,  Wicklow  and  Wexford.  The  Dakley  quar- 
ries are  said  to  have  been  opened  in  1680  and  regularly 
worked  ever  since.  Many  of  the  granites  are  gray  muscovite- 
biotite  irruptives.  In  some  cases  the  prevailing  feldspar, 
crthoclase,  is  a  delicate  pink.  Such  stones  are  susceptible 
of  a  high  polish  and  largely  sought  for  decorative  work. 

Scotland. — According  to  J.  Watson  granite  was  quarried 
in  Scotland  as  early  as  1T(U  and  used  for  paving  the  streets 
of  London.  The  granites  quarried  in  the  Aberdeen  district 


Fig.  88. — Polished  slab  of  Imperial  blue  granite,  Woodbury,  Ver- 
mont. Photo,  by  C.  H.  Richardson. 

and  immediate  vicinity  range  from  fine  to  medium  in  texture, 
and  in  color  from  a  light  silvery  gray,  blue  gray,  dark  gray 
to  red.  The  Peterhead  granite  falls  into  two  types.  One  is 
of  blue  color  and  the  other  is  red.  They  grade  from  medium 
to  coarse  in  texture.  The  red  Peterhead  has  been  introduced 
in  nearly  all  the  countries  of  the  world  as  a  decorative  stone 
of  great  beauty.  Its  mineral  composition  is  quartz,  ortho- 
clase,  albite  and  biotite.  The  Aberdeen  stone  bears  oligoclase 
in  the  place  of  albite.  (See  Figs.  103  and  104.) 

Egypt. — The  term  syenite  came  from  the  town  of  Syene, 
Egypt*  where  the  irruptive  granitic  rocks  of  the  country  were 
quarried  about  1300  years  before  the  beginning  of  the  Christian 
era  and  fashioned  into  colossal  statues,  obelisks  and  sarco- 
phagi. The 'true  syenite  of  today  is  a  plutonic  rock  con- 


GRANITES 


99 


100 


BUILDING   STONES   AND    CLAYS 


si  sting  of  orthoclase  and  hornblende.  The  Egyptian  syenite 
is  a  granite  whose  mineral  composition  is  quartz,  orthoclase,. 
(and  a  whitish  feldspar),  biotite  and  hornblende.  The  obelisk 
in  Central  Park,  New  York  City,  came  from  Syene,  Egypt. 
All  of  its  hieroglyphics  have  had  to  be  recut  because  the  stone 
disintegrates  rapidly  in  America,  although  permanent  under 
Egyptian  skies. 

Sweden. — The   Swedish  rose  granite  from  the   Graversfors 
district  has  dark  red  orthoclase   with  deep  blue  and  purple  quartz. 
Fig.  105.) 


Fig.  90. — Post  Office,  New  Bedford,  Massachusetts,  built  of  Wood- 
bury  gray  granite  from  Woodbury,  Vermont.  By  courtesy  of  G.  H. 
Bickford. 

Practically  all  countries  of  the  world  are  producers  of 
granite  in  some  quantity.  Many  of  these  granites  are  highly 
decorative  stones  while,  others  are  better  suited  for  construc- 
tional purposes. 

INDUSTRIAL  FACTS  ABOUT  GRANITE 

Uses. — The  use  to  which  a  granite  will  be  put  depends 
upon  its  color,  texture,  hardness,  compressive  test,  tensile 
strength,  susceptibility  of  polish,  and  in  part  to  its  mineral- 


GRANITES 


)£  BUILDING    STONES   AND    CLAYS 


Fig.  93. — Soldiers'  and  Sailors'  Memorial,  Wichita,  Kansas,  built 
of  Vermont  white  granite.  By  courtesy  of  the  Woodbury  Granite 
Company. 


104 


BUILDING    STONES   AND    CLAYS 


I 


GRANITES 


105 


Fig.  95. — Polished  disc  of  white  granite,  West  Dummerston,  Ver- 
mont, from  quarries  of  W.  N.  Flynt  Granite  Company.  Photo,  by 
C.  H.  Richardson. 


Fig.  96. — Granite  quarry,  Bethel,  Vermont,   showing  sheeted  struc- 
ture.    Photo,  by  C.  H.  Richardson. 


106 


BUILDING    STONES   AND    CLAYS 


Fig.  97. — West  front  of  State  Capitol,  Madison,  Wisconsin,  built 
of  Bethel  white  granite.  By  courtesy  of  the  Woodbury  Granite 
Company. 


GRANITES 


107 


108 


BUILDING    STONES   AND    CLAYS 


Fig.  99.— Building  of  Union  Trust  Company,  Rochester,  New  York, 
built  of  Bethel  white  granite.  By  courtesy  of  the  Woodbury  Granite 
Company. 


GRANITES 


109 


110 


BUILDING    STONES   AND    CLAYS 


Fig.  101. — Polished  slab  of  nordmarkite  from  the  northeast  side  of 
Mount  Ascutney,  Windsor,  Vermont.     Photo,  by  C.  H.  Richardson. 


Fig.    102. — Polished   disc    of    porphyritic    granite    showing   "Horses 
Teeth."     Photo,  by  C.   H.   Richardson. 


GRANITES 


111 


Fig.    103. — Polished    slab    of    Scotch    granite,    P'eterhead,    Scotland. 
Photo,  by  C.  H.  Richardson. 


1 


Fig.  104. — Monument  of  Scotch  granite  in  Green  Mountain  Ceme- 
tery, Montpelier,  Vermont,  erected  in  1882.  Photo,  by  C.  H.  Rich- 
ardson. 


112 


BUILDING    STONES   AND    CLAYS 


ogical  composition.  The  white  and  light  gray  granites  are 
especially  desirable  for  constructional  purposes.  The  dark 
gray,  pink  and  red  granites  are  used  more  largely  for  monu- 
mental, inscriptional  stone  and  for  decorative  interior  work. 
Granites  like  that  of  Quincy,  Mass.,  have  been  extensively 
used  in  this  line  of  wrork,  as  well  as  the  red  granite  of  Peter- 
head,  Scotland.  Granite  is  also  used  for  trimming,  curbing, 
paving,  etc.  It  is  often  crushed  and  used  for  permanent  road 
material.  But  the  basic  irruptives  have  better  cementing 


Fig.   105. — Monument  of  Swedish  granite  set   in  the  Catholic  ceme- 
tery,   Montpelier,   Vermont.      Photo,   by   C.   H.   Richardson. 


qualities  and  their  feldspars  are  equally  resistant  to  abrasion. 
Therefore  they  make  the  better  road  metal.  Granites  are 
also  used  for  ballast,  riprap  and  rubble. 

Quarrying. — The  object  in  quarrying  granite  is  to  secure 
symmetrical  rectangular  blocks  with  the  least  possible 
waste  of  material,  time  and  money.  Advantage  is  taken  of 
the  sheeted  structure  of  quarries  whenever  that  structure  is 


GRANITES 


113 


Fig.   106. — Channelling  machine   at  work  on  Wetmore  and  Morse 
quarry,    Barre,  Vermont.     Photo,  by  C.   H.  Richardson. 


114  BUILDING    STONES    AND    CLAYS 

of  a  marked  character.  The  quarry  is  opened  in  such  a  manner 
that  the  quarry  floor  slopes  away  from  the  working  face.  In 
many  quarries  no  blasting  powder,  rend  rock,  dualline,  dyna- 
mite or  nitroglycerine  is  used.  Where  the  sheets  are  much 
thicker  than  can  be  split  with  wedges,  Lewis  holes  or  Knox 
holes  are  drilled  at  varied  intervals  to  depths  depending  upon 
the  thickness  of  the  block  desired  and  then  fired  simultan- 
eously. The  blocks  are  afterward  split  with  wedges  into 
smaller  dimensions.  Explosives  often  develop  fracture  planes 
that  are  not  visible  until  the  stone  is  polished  or  dressed. 
They  are  planes  of  weakness.  They  also  make  possible  a 
more  rapid  disintegration  of  the  finished  product. 


Fig.  107. — Rope-driven  traveling  crane  made  by  the  Lane  Manu- 
facturing Company,  Barre,  Vermont.  By  Courtesy  of  the  Lane 
Manufacturing  Company. 


Polishing  Granite. — The  most  expensive  finish  for  granite 
io  the  polish.  The  process  brings  out  the  grain  and  mottle 
of  the  stone  in  its  full  beauty.  The  process  of  polishing 
granite  is  slow  and  costly,  but  the  finished  product  is  hand- 
some, durable  and  easily  cleaned.  The  rough  block  is  first 
ground  by  heavy  iron  scrolls  to  an  even  surface.  After 
thorough  washing  the  stone  is  rubbed  with  carborundum 
which  further  smooths  the  surface.  The  stone  is  again  washed 
and  putty  powder  is  applied  and  rubbed  into  the  surface  with 
heavy  felt  buffers.  It  is  this  final  process  which  gives  the 
gloss  and  closes  the  surface  to  a  uniform  finish. 

Good  granite  when  properly  polished  will  hold  its  gloss 
for  fifty  years  or  more  in  spite  of  exposure  to  the  corrosive 


GRANITES 


115 


116 


BUILDING    STONES   AND    CLAYS 


agents  of  the  atmosphere.  If  oxalic  acid  is  used  in  the  process 
of  buffing  in  the  place  of  putty  powder  the  life  of  the  stone 
i?  short.  (See  Figs.  100,  107,  108,  109,  110,  111,  112,  113,  11.4, 
115,  116  and  117.) 


Fig.  109. — Carborundum  saw  at  work  in  granite  in  the  sheds  of  the 
Woodbury  Granite  Company,  Hardwick,  Vermont.  Photo,  by  C.  H. 
Richardson. 


Compression  Tests. — A  few  compression  tests  are  given  as 
matter  of  reference. 

Bay  of  Fundy 11,9  Ui  Ib.  to  the  cubic  inch 

Platte  Canon,  Colo 14,634  Ib. 

Westerly,  R.  I 1 7,500  Ib. 

Quincy,  Mass 17,750  Ib. 

Vinalhaven,  Me .....18,000  Ib. 

Barre,  Vt 1 9,000  Ib. 

Richmond,  Va .....19,104  Ib. 

Rockport,   Mass 1 9,750  Ib. 

Milford,    Conn 22,610  Ib. 

East  St.  Cloud,  Minn 28,000  Ib. 

Bethel,  Vt.  ...  ....33,153  Ib. 


GRANITES  117 

Chemical  Analyses. — A  few  analyses  of  granites  are  ap- 
pended here  as  a  matter  of  reference. 

1.  Granite  from  the  quarry  at  North  Jay,  Maine.  Analysis 
made  by  Prof.  J.  E.  Wolff  of  Harvard  University,  Cambridge, 
Mass. 

SiO2,  silica 71.54* 

TiO2,  titanium  dioxide  0.84 

A12O3,  alumina  14.24: 

Fe2O3,  ferric  oxide  0.74 

FeO,  ferrous  oxide  1.18 

CaO,    lime .'....     0.98 

MgO,  magnesia  0.34 

Na2O,  soda 3.39 

K2O,  potash 4.73 

H2O,  water 0.61 

S,  sulphur Trace 

,  carbon  dioxide  ..  ...Trace 


98.59 


2.  Granite  from  High  Isle  quarry,  Knox  County,  Maine. 
Analysis  made  by  Prof.  J.  F.  Kemp,  Columbia  University, 
New  York  City. 

SiO2,  silica : 74.54 

A12O3,  alumina  13.30 

Fe2O3,  ferric  oxide  0.92 

FeO,  ferrous  oxide  0.79 

CaO,  lime 1.26 

MgO,  magnesia 0.009 

MnO,  manganous  oxide 0.51 

Na2O,  soda  3.69 

K2O,  potash 5.01 

S,  sulphur  0.038 


100.067 


118  BUILDING    STONES    AND    CLAYS 

3.  Granite  from  Concord,  N.  H.  Analysis  made  by  Prof 
W.  O.  Crosby,  Massachusetts  Institute  of  Technology,  Bos- 
ton, Mass. 

SiO,,   silica    74.17 

A1,O.,,  alumina  ..  1  1,15 

Fe2O,,  ferric  oxide  

FeO,  ferrous  oxide  

CaC),  lime    . 

MgO,   magnesia   ...; (  .<>3 

Na2O,   soda 

KoO,  potash 

ILO,   water  .... 

H,O,  water  combined 

S,  sulphur   0.27 

CO.,,  carbon  dioxide  ..  0.25 


100.21 

4.   Granite  from  Bethel,  Vermont.     Analysis  made  by  C.  F. 
McKenna  of  New   York   City. 

SiO,,  silica 77.52 

A1,O,,  alumina  .    1(5. 78 

FeO,  ferrous  oxide 0.84 

CaO,  lime  .. 2.5(5 

MgO,   magnesia   .  0.32 

Na,O,   soda   .  1.21. 

K,( ),  potash  ().(52 

Loss   on    ignition 0.33 


100.18 
5.   Granite  from  the  Wells-Lamson  "  dark   Barre  "  quarries, 

Barre,    Vermont.      Analysis    made    by    William    C.    Day    at 

Swarthmore   College,   Pennsylvania. 

SiO,,  silica  ..   (5!). 5(5 

Al2Oa,  alumina  15. 08 

Fe2O:i,  ferric  oxide  '. 2.(>5 

CaO,   lime    1.7'0 

MgO,   magnesia  Trace 

MnO,  manganous  oxide  Trace 

Na,O,   soda   .  5.38 

K26,  potash    .  4.31 

Loss  on  ignition, 
CO,  and  moisture...  1.02 


100.  OG 


GRANITES'  119 

6.  Granite     from     the    Hardwick     quarry,     Quincy,     Mass. 
Analysis  made  by  H.  S.  Washington,  Washington,  D.  C. 

SiO2,  silica  73.93 

TiO2,  titania  . 0.18 

A12O3,  alumina 12.29 

Fe2O3,  ferric  oxide       2.91 

FeO,  ferrous  oxide 1.55 

MnO,  manganous  oxide Trace 

CaO,  lime    0.31 

MgO,  magnesia 0.04 

Na,O,  soda 4.66 

K26,  potash   4.63 

H2O,  water  above  110°  C...  0.41 


100.91 

7.  Granite  from  Milford,  Massachusetts.    Analysis  made  by 

Prof.  L.  P.  Kinnicut,  Worcester  Polytechnic  Institute,  Wor- 
cester, Mass. 

SiO2,  silica 77.08 

A12O3,  alumina 12.54 

FeO,  ferrous  oxide 0.95 

CaO,   lime 0.75 

MgO,  magnesia 0.01 

Na2O,  soda  3.64 

K26,  potash 4.99 


99.96 


8.  White   granite    from    W.    N.    Flynt    Granite    Company's 
(juarry,  West  Dummerston,  Vermont. 

SiO2,  silica 72.80 

FeO,  oxide  of  iron Trace 

A12O3,  alumina 19.40 

CaO,   lime 1.00 

Na2O,  soda 4.17 

K2O,  potash  2.63 


100.00 


120 


BUILDING    STONES   AND    CLAYS 


ROCKS  RELATED  TO  GRANITES  AND  IN  PART 
INCLUDED  IN  THE  ABOVE  DESCRIPTION 

Aplite. — Aplite  is  a  fine  grained  aggregation  of  quartz  and 
feldspar,  with  a  little  muscovite,  often  occurring  in  dikes. 
When  a  granite  bears  but  few  phenocrysts  of  the  ferromag- 
nesian  minerals  it  is  called  aplitic.  The  contrast  in  color 
between  the  quartz  and  feldspars  is  not  strong. 


Fig.    110.— Polishing   wheel    at   work,    Hardwick,   Vermont. 
by  Smart. 


Photo. 


Monzonite. — The  monzonites  have  both  the  monoclinic  feld- 
spar, orthoclase,  and  the  triclinic  lime-soda  feldspar,  or  plagio- 
clase,  in  approximately  equal  amounts.  The  quartz  monzon- 
ites .are  granites  in  which  the  plagioclase  equals  or  exceeds 
the  orthoclase. 


GRANITES  12 1 

Syenite. — This  rock  is  intermediate  between  a  true  granite 
and  a  diabase.  Its  mineralogical  composition  is  orthoclase 
and  hornblende.  If  the  micas  displace  the  hornblende  the 
rock  is  called  a  mica  syenite.  The  stone  is  often  susceptible 
of  a  high  polish  and  commercially  used  under  the  name  of 
granite. 


Fig.  111. — Gang  of  5  saws  cutting  a  block  of  granite,  Hardwick, 
Vermont.  Photo,  by  C.  H.  Richardson. 

Porphyry. — This  term  is  not  to  be  confused  with  the  por- 
phyritic  granites  where  phenocrysts  of  feldspar  appear  more 
than  .4  inch  in  diameter.  The  term  as  there  used  applies  only 
to  texture.  The  term  porphyry  as  here  used  embraces  two 
types  of  acidic  intrusives  in  which  some  mineral  constituent 
is  porphyritically  developed  in  a  ground  mass  that  is  not  in- 


BUILDING    STONES    AND    CLAYS 


_  Fig.  112. — Granite  lathe  working  on  2  pieces  of  granite  at  the  same 
time.     By  courtesy  of  G.  H.   Bickford. 


Fig.    113. — Pirie    tool    sharpening   machine,    showing   belt    conveyor, 
forge  and  piles   of  tools.      Photo,  by  C.  H.    Richardson. 


GRANITES 


123 


•| 


Fig.  114. — McDonald  surfacing  machine  in  sheds  at  Hardwick,  Ver- 
mont.    By  courtesy  of  G.  H.  Bickford. 


124 


BUILDING    STONES   AND    CLAYS 


dividualized.  It  requires  a  petrographic  examination  to  ascer- 
tain the  mineral  content  of  the  glassy  ground  mass.  Quartz 
porphyries  bear  phenocrysts  of  quartz,  or  quartz  and  ortho- 
clase,  in  a  glassy  ground  mass.  In  an  orthoclase  porphyry 


Fig.  115. — Interior  of  the  big  shed  of  the  Woodbury   Granite  Com- 
pany at  Bethel,  Vermont.     Photo,  by  C.  H.  Richardson. 


Fig.  116. — Tripple  granite  shed  of  the  Woodbury  Granite  Company 
at  Bethel,  Vermont.     Photo,  by  C.   H.   Richardson. 


GRANITES 


125 


the  phenocrysts  are  orthoclase  and  quartz  is  absent.  •  The 
porphyries  possess  a  kindred  variation  in  color  with  the 
granites  shading  even  to  black.  Unlike  the  granites  they  are 


Fig.  117. — Method  of  chaining  a  large  block  of  Bethel  white  granite. 
By  courtesy  of  the  Woodbury  Granite  Company. 


Fig.  118.— Hand  polished  slab  of  porphyry,  Saugus,  Massachusetts. 
Photo,  by  C.  H.  Richardson. 


120  BUILDING    STONES   AND    CLAYS 

without  rift  and  grain.  Many  of  them  take  a  high  polish  and 
some  of  them  are  used  with  good  results  as  decorative  ma- 
terial. (See  Fig.  118.) 

Liparite. — The  liparites  are  extrusive  rocks  rather  than 
intrusive  like  the  granites.  Their  essential  mineralogical  com- 
position is  quartz  and  sanidine.  Sanidine  is  a  glassy  variety 
of  orthoclase.  The  liparites  grade  in  texture  from  the  -clear 
glassy  forms  on  the  one  hand  to  holocrystalline  porphyritic 
forms  on  the  other.  They  are  not  widely  used. 

Rhyolite. — Rhyolite  is  the  eruptive  equivalent  of  granite 
and  has  the  same  chemical  composition.  •  It  commonly  con- 
tains more  or  less  of  undifferentiated  glass.  Ohsidian  is  the 
wholly  vitreous  variety.  These  rocks  occur  in  large  masses 
in  many  of  the  western  states,  and  in  Colorado  they  are  used 
for  structural  purposes. 


Fig.  119. — Polished  boulder  of  porphyritic  ciiorite,  Washington, 
Vermont.  Photo,  by  C.  H.  Richardson. 

Trachyte. — Trachyte  is  the  eruptive  equivalent  of  syenite. 
Like  a  syenite  when  it  bears  mica  instead  of  hornblende  it  is 
called  a  mica  trachyte.  Trachytes  are  of  small  significance  as 
structural  material.  Between  the  trachytes  and  the  syenites 
there  are  intermediate  forms  analogous  to  the  quartz  por- 
phyries. 

Phonolite. — This  rock  receives  its  name  from  the  fact 
that  it  rings  clearly  when  struck  with  a  hammer.  Its  chief 
difference  from  trachyte  is  that  it  bears  either  nephelite  or 
leucite  in  its  mineral  composition. 

Andesite. — This  is  a  basic  eruptive.  It  is  marked  by  the 
presence  of  plagioclase  rather  than  orthoclase.  Its  ground 
mass  is  felsitic.  If  quartz  is  present  in  any  appreciable 
quantity  the  stone  is  called  a  quartz  andesite.  The  varieties 


GRANITES  m 

depending  upon  the  prevailing  ferromagnesian  mineral  present 
are  hornblende  andesite,  augite  andesite,  hypersthene  andesite, 
mica  andesite.  These  varieties  are  used  somewhat  for  struc- 
tural purposes. 

Diabase. — This  rock  is  often  quarried  and  sold  under  the 
name  of  "black  granite."  It  is  a  basic  intrusive  whose  essen- 
tial mineralogical  cemposition  is  plagioclase  and  augite. 
Olivine  is  often  present,  in  which  case  the  rock  takes  the  name, 
olivine  diabase.  The  diabases  are  massive  microcrystalline 
rocks,  without  the  rift  and  grain  characteristic  of  granites. 
They  are,  however,  quarried  to  some  extent  and  used  for 
decorative  interior  work.  They  are  susceptible  of  a  high 


Fig.  120. — Smoothed  slab  of  orbicular  diorite,  Dehesa,  San  Diego 
County,  California.  Photo,  by  C.  H.  Richardson. 

polish,  and  the  polished  face  receives  a  lettering  legible  to  a 
greater  distance  than  many  of  the  granites.  The  diabases, 
however,  are  best  suited  for  the  construction  of  permanent 
roads,  for  they  have  the  requisite  resistance  to  abrasion  and 
the  desired  cementing  qualities.  (See  Fig.  11.) 

Basalt. — The  term  basalt  was  formerly  used  for  the  dark 
basic  volcanic  rocks  of  Tertiary  or  post-Tertiary  age.  The 
time  distinction  is  obsolete.  In  addition  to  the  necessarv 


128  BUILDING    STONES    AND    CLAYS 

plagioclase  and  augite,  basalts  almost  always  bear  olivine  as 
an  essential  component.  The  rather  rare  olivine-free  basalt- 
marks  a  transition  to  the  augite  andesites.  The  basalts  lack 
the  characteristic  rift  and  grain  of  granites,  but  they  are  ex- 
tensively used  in  the  construction  of  permanent  roads. 

Diorite. — The  diorites  are  basic  irruptives,  macrocrystalline, 
whose  essential  constituents  are  plagioclase  and  hornblende. 
Phenocrysts  of  the  prevailing  feldspar  often  appear,  when  the 
stone  is  called  a  porphyritic  diorite.  These  rocks,  like  the 
diabases,  are  without  the  rift  and  grain  of  the  granites.  They 


Fig.  121. — Boulder  of  gneiss  from  near  Arapahoe  Peak,  Colorado. 
Photo,  by  T.  C.  Hopkins. 

make  most  excellent  road  metal  for  the  same  reason  as  the 
diabase.  They  receive  a  high  polish  and  were  it  not  for  the 
question  of  expense  in  working  would  be  a  valuable  deco- 
rative stone.  (See  Figs.  119  and  120.) 

Gabbro. — This  term  was  long  used  for  a  basic  igneous  rock 
whose  prevailing  ferromagnesian  mineral  was  the  bladed  or 
flattened  pyroxene,  diallage.  The  term  is  now  largely  reserved 
for  field  use.  Gabbros  occur  in  large  masses  in  the  Adiron- 
dack region.  The  hypersthene  gabbro  whose  prevailing  feld- 


GRANITES  ]2f> 

spar  is  labradorite  is  a  norite  which  is  quite  extensively 
quarried  near  Keeseville,  N.  Y.,  and  sold  as  Keeseville  granite. 
Diabases,  diorites  and  gabbros  all  appear  in  the  marts  of  trade 
under  the  name  of  black  granites. 

Norite. — The  norites  belong  to  the  gabbro  family,  their  es- 
sential minerals  are  plagioclase,  usually  laboradorite,  and 
some  orthorhombic  pyroxene,  usually  hypersthene.  Small 
quantities  of  biotite  and  hornblende  may  be  present.  Vari- 
eties bearing  olivine  are  also  known.  The  norite  of  Keeseville, 
N.  Y.,  is  susceptible  of  a  high  polish. 


Fig.  122. — Anticline  and  quartz  vein  in  gneiss,  Washington,  Ver- 
mont, showing  the  intense  pressure  to  which  the  rock  has  been  sub- 
jected. Photo,  by  C.  H.  Richardson. 

Gneiss. — A  gneiss  is  a  metamorphic  rock  of  sedimentary  or 
igneous  origin.  Its  mineralogical  composition  is  identical 
with  that  of  granite.  It  differs  from  granite  in  having  its  fer- 
romagnesian  mineral  arranged  in  parallel  layers,  instead  of 
being  uniformly  scattered  throughout  the  rock  mass.  It  there- 
fore is  less  resistant  to  compressive  stresses  than  the  granites, 
especially  if  pressure  be  applied  parallel  with  the  schistosity. 

9 


130 


BUILDING    STONES   AND    CLAYS 


The  names  of  the  different  varieties  are  determined  by  the 
prevailing  ferromagnesian  mineral.  If  the  gneiss  results  from 
the  shearing  of  granite  masses  it  is  called  a  granite  gneiss  and 
is  simply  a  metamorphosed  granite.  If  it  results  from  the 
metamorphism  of  feldspathic  sediments  it  is  called  a  para- 
gneiss.  (See  Figs.  121  and  122.) 

Volcanic  Tuff. — A  volcanic  tuff  is  a  deposit  of  volcanic  ash 
which  has  become  consolidated.  This  eruptive  occurs  as  a 
building  stone  at  Los  Berros,  San  Luis  Obispo  County,  Cali- 
fornia. The  outcrop  is  on  the  south  side  of  Los  Berros  creek. 


™ 


Fig.  123. — Quarry  in  volcanic  tuff,  Los  Berros,  San  Luis  Obispo 
County,  California.  The  material  is  used  for  building  purposes. 
Photo,  by  T.  C.  Hopkins. 

In  the  quarry  two  distinct  beds  of  tuff  are  readily  discerned. 
The  upper  bed,  from  10  to  12  feet  thick,  thins  out  toward  the 
west.  It  lies  without  any  parting  on  the  smooth  surface  of  an 
older  bed,  dipping  slightly  to  the  east.  The  upper  tuff  is  of 
more  regular  character  and  harder  than  the  underlying  tuff.  It 
breaks  in  large  but  irregular  blocks.  The  lower  tuff  is  much 
harder  than  the  upper,  has  a  metallic  ring  and  breaks  in  small 
blocks  with  curved  faces  like  glass.  (See  Fig.  123.) 


GRANITES 


131 


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132  BUILDING    STONES    AND    CLAYS 

REFERENCES 

Buckley,  E.  B.    Building  and  Ornamental  Stones  of  Wisconsin ; 

Bull.  Geol.  Survey,  No.  4,  Madison,  Wis.,   1.898. 
Coons,  Altha  T.    The  Stone  Industry  in  1904.     Min.  Res.  U.  S., 

1904. 

Dale,  T.  N.    The  Granites  of  Maine;  Bull.  313,  U.  S.  G.  S.,  1907. 
Dale,  T.   N.    The  Chief  Commercial  Granite  of  Massachusetts, 

New  Hampshire  and  Rhode  Island;  Bull.  354,  U.  S.  G.  S. 

1908. 
Dale,  T.  N.    The  Granites  of  Vermont;  Bull.  415,  U.  S.  G.  S., 

1909. 
Daly,  R.  A.   The  Geology  of  Ascutney  Mountain,  Vt. ;  Bull.  209, 

U.  S.  G.  S.,  1903. 

Day,  W.  C.    Stone;  Min.  Res.  U.  S.  G.  S.,  1899. 
Harris,  G.  F.   Granite  and  Our  Granite  Industries ;  London,  1888. 
Howe,  J.  A.    The  Geology  of  Building  Stones ;  E.  Arnold,  Lon- 
don, 1910. 

Hull,  E.  A.  Treatise  on  the  Building  and  Ornamental  Stones  of 
Great  Britain  and  Foreign  Countries;  London,  1872. 

Lewis,  J.  V.  Building  Stones  of  New  Jersey;  N.  J.  Geol.  Sur- 
vey, 1908. 

Mathews,  E.  B.  The  Granite  Quarries  of  Maryland  ;  Kept,  of 
Maryland  Geol.  Sur.  Vol.  2,  1898. 

Merrill,  G.  P.  Stones  for  Building  and  Decoration ;  J.  Wiley 
and  Sons,  1902. 

Parks,  W.  A.  The  Building  Stones  of  Canada ;  Can.  Mines 
Branch,  Vol.  I:  Rept.  No.  100  (Ontario);  1912,  Vol.  11: 
Rept.  No.  203  (Maritime  Provinces)  ;  1914.  Vol.  Ill:  Rept. 
No.  279  (Quebec)  ;  1914.  Vol.  IV:  Rept.  No.  388  (Western 
Provinces)  ;  191(5. 

Perkins,  G.  H.  Report  on  the  Marble,  Slate  and  Granite  Indus- 
tries of  Vermont;  1898. 

Richardson,  C.  H.  Areal  and  Economic  Geology  of  North- 
eastern Vermont ;  Rep.  of  Vermont  State  Geologist,  1905- 
1906. 

Richardson,  C.  H.,  A.  E.  Brainerd  and  D.  J.  Jones.  The 
Geology  and  Mineralogy  of  Hardwick  and  Woodbury,  Vt. ; 
Report  of  Vermont  State  Geologist,  1914. 

Ries,  H.  Economic  Geology;  John  Wriley  and  Sons,  191(5. 


GRANITES  133 

Ries,  H.,  and  T.  L.  Watson.     Engineering  Geology,  John  Wiley 

&  Sons,  1914. 
Tarr,  R.  S.  Economic  Geology  of  the  United  States,  with  Briefer 

Mention  of  Foreign  Mineral  Products ;  New  York,  1895. 
Watson,  J.  Building  Stones ;  Cambridge  University  Press,  1911. 
Watson,  T.  L.    A  Preliminary  Report  on  a  Part  of  the  Granites 

and  Gneisses  of  Georgia ;  Bull.  9A,  Georgia  Geol.  Survey, 

1902. 


CHAPTER  IV 

LIMESTONES,  DOLOMITES  AND  MARBLES 

Definition. — A  limestone  is  any  rock  mass  consisting  essen- 
tially of  calcium  carbonate,  CaCO3,  or  of  calcium  carbonate 
intermingled  with  more  or  less  magnesium  carbonate.  The 
calcium  carbonate  has  been  separated  from  water,  rendered 
insoluble  and  accumulated  by  the  action  of  living  organisms 
of  various  kinds.  Such  deposits  may  be  mechanically  broken 
up  and  redeposited,  or  they  may  be  taken  into  solution, 
carried  away  and  precipitated  elsewhere.  Some  possible  ex- 
ceptions to  this  rule  are  cited  later  under  the  caption  of  the 
origin. 

A  dolomite  is  any  rock  consisting  essentially  of  calcium 
carbonate  and  magnesium  carbonate,  CaCO3,  MgCO3.  Geo- 
logically speaking  a  dolomite  may  contain  a  large  amount  of 
admixed  calcite.  Mineralogically,  dolomite  means  a  definite 
chemical  compound  of  formula  CaCO3,  MgCCX.  Limestones 
containing  more  than  5  per  cent  of  magnesium  carbonate  are 
dolomitic.  The  magnesium  carbonate  of  the  dolomites  has 
been  added  to  organic  limestones  which  were  originally  free 
from,  or  poor  in,  magnesia.  The  unstable  forms  of  calcium 
carbonate,  aragonite  and  conchite  take  up  magnesia  quite 
readily.  According  to  K.  Weinschenk  calcite  cannot  be 
altered  to  dolomite.  Dolomites  are  distinctly  crystalline,  often 
porous  and  filled  with  drusy  cavities. 

From  a  geological  standpoint  a  marble  is  a  metamorphosed 
limestone.  It  is  distinguished  from  a  limestone  by  its  crystal- 
lization, coarser  grain,  compactness  and  purer  colors.  If  pure, 
it  is  often  very  massive  and  shows  no  signs  of  schistose  cleav- 
age, even  where  its  association  with  schists  is  such  as  to  indi- 
cate that  it  must  have  been  subjected  to  enormous  pressure 
and  shearing  stresses. 

Dolomitic  limestones  pass  by  metamorphism  into  dolomitic 
marbles.  We  therefore  have  both  calcite  marbles  and  dolo- 
mite marbles.  A  metamorphosed  calcareous  rock  is  often 
called  a  marble  whether  it  contains  magnesia  or  not.  From  a 
petrographical  and  a  chemical  standpoint  there  is  an  impor- 
tant difference  between  a  calcite  marble  and  a  dolomite 

134 


LIMESTONES,  DOLOMITES  AND  MARBLES      135 

marble.  This  holds  especially  true  in  respect  to  the  associated 
minerals  they  are  apt  to  contain  when  impurities  were  origin- 
ally present  in  them.  The  pure  statuary  marbles  like  those  of 
Marble,  Colorado,  Western  Vermont  and  Carrara,  Italy,  con- 
tain little  else  than  the  mineral  calcite.  Dolomite  marbles 
usually  contain  some  calcite  in  addition  to  the  dolomite  crys- 
tals. From  a  purely  commercial  standpoint  a  marble  is  any 
limestone  or  dolomite,  whether  metamorphosed  or  not,  sus- 
ceptible of  a  polish  and  suited  for  decorative  interior  work  or 
the  purposes  of  massive  construction. 

Impurities. — Limestones  vary  widely  in  their  composition. 
They  range  from  25  per  cent  CaCO3  to  theoretically  100  per 
cent  CaCO3.  The  impurities  are  uncombined  carbon  which 
imparts  a  dark  gray  or  black  color  to  the  rock,  clayey  matter 
which  gives  limestone  a  drab  or  gray  color,  pyrite,  siderite, 
talc,  serpentine,  micas,  amphiboles,  pyroxenes  and  sand.  Green- 
sand  marl  and  phosphatic  particles  are  sometime^  present. 
Bituminous  matter  and  even  hydrogen  sulphide  may  be  en- 
cased in  limestones.  The  former  shows  the  presence  of  bi- 
tumen when  heated,  and  the  latter  variety  emits  an  offensive 
odor  when  struck  with  a  hammer.  Such  a  limestone  is  repre- 
sented at  Chatham,  Canada,  and  in  western  Vermont. 

Texture. — The  texture  of  the  calcareous  rocks  is  as  varied 
as  their  composition.  They  range  from  the  soft,  friable,  fine 
grained  chalk  to  the  compact  and  crystalline  types.  As  a  rule 
the  older  formations  are  the  more  compact  and  crystalline, 
while  the  younger  formations  are  more  apt  to  be  friable. 

Varieties. — The  numerous  varieties  are  based  upon  several 
different. factors  as  structure,  chemical  composition,  mode  of 
origin,  uses,  etc. 

A  pure  marble  consists  of  calcite  crystals  in  a  crystalline, 
granular  aggregation.  Saccharoidal  marble  is  a  variety  that 
closely  resembles  loaf  sugar  in  texture.  Common  compact 
limestone  is  often  amorphous  and  homogeneous.  A  micro- 
scopic investigation  reveals  it  to  be  an  aggregation  of  crystal- 
line calcium  carbonate.  Hydraulic  limestone  which  has  so 
large  a  significance  from  an  engineering  standpoint  is  a 
variety  that  contains  10  per  cent  or  more  of  silica  and  the 
proper  amount  of  clayey  matter  to  make  a  cement  that  when 
the  stone  is  burned  will  set  under  \vater.  Lithographic  lime- 
stone that  has  been  used  extensively  in  the  preservation  of 
stock  patterns  is  a  fine  grained  magnesian  variety  with  its 
best  representative  found  at  Solenhofen,  Germany.  Oolitic 
limestone  consists  of  small,  rounded,  concretionary  grains 


136 


BUILDING    STONES   AND    CLAYS 


about  the  size  of  the  egg  of  a  brook  trout.  A  dolomitic  lime- 
stone is  one  containing  5  per  cent  or  more  of  magnesium 
carbonate.  In  its  metamorphism  it  passes  into  a  dolomitic 
marble.  A  true  dolomite,  however,  would  be  represented  by 
the  double  molecule,  CaCO3,  MgCO3,  which  characterizes 
some  of  our  most  handsome  decorative  marbles.  There  is 
every  stage  and  gradation  between  calcite  on  the  one  hand 
and  magnesite  on  the  other.  Travertine,  known  also  as  cal- 
careous tufa,  represents  a  chemical  precipitate.  Mexican  onyx 
is  a  massive  variety  of  travertine  that  is  highly  prized  for  its 
translucency  and  variety  of  colors.  Stalactite  is  the  variety 


Fig.    124. — Sawn    slab    of    fossiliferous    marble. 
Richardson. 


Photo,    by    C.    H. 


that  forms  on  the  roofs  of  caves  and  stalagmite  the  one  that 
forms  in  a  similar  manner  upon  the  floors  of  caves.  When  the 
two  varieties  meet  they  form  a  pillar.  Coquina  is  a  variety 
that  consists  of  broken  shells  held  together  by  a  cement  of 
lime.  The  more  compact  massive  forms  are  used  for  building 
purposes.  A  coralline  limestone  is  one  consisting  essentially 
of  fragments  of  coral.  A  fossiliferous  limestone  is  one  con- 
taining any  identifiable  fragment  of  the  testa  of  some  former 
animal.  Such  limestones  are  named  from  the  prevailing 


LIMESTONES,  DOLOMITES  AND  MARBLES      137 

species  present,  as  crinoidal  limestone  when  the  fossils  are 
the  fragments  of  crinoidal  stems.  (See  Figs.  124  and  125.) 

Origin. — The  origin  of  limestones,  dolomites  and  marbles 
is  very  diverse.  The  primary  source  is  to  be  found  in  the  de- 
composition of  igneous  rocks  by  carbonated  waters.  Calcium 
carbonate  is  taken  into  solution  in  ground  water,  springs  and 
rivers,  and  subsequently  withdrawn  from  solution  by  a  va- 
riety of  processes.  It  is  deposited  as  a  chemical  sediment 
from  hot  springs  and  sea  water  and  often  precipitated  as  a 
cement  in  other  rocks. 

Waters  charged  with  carbon  dioxide  become  a  potent  sol- 
vent for  rock  constituents.  This  effect  is  illustrated  by  the 
limestone  caves  m  Kentucky  and  the  Luray  Caverns  in  Vir- 


Fig.  125. — Cross  section  of  coralline  marble,  Iowa  City,  Iowa. 
Photo,  by  C.  H.  Richardson. 

ginia.  The  surchaged  \vaters  when  relieved  of  pressure 
deposit  their  load  in  some  of  the  various  forms  of  travertine. 
The  stalactitic  and  stalagmitic  marbles  fall  into  this  class.  By 
this  process  also  large  masses  of  the  compact  variety  known 
as  onyx  are  produced. 

Rivers  flowing  over  limestone  areas  carry  a  certain  amount 
of  calcium  carbonate  in  solution  into  the  sea.  A  direct  pre- 
cipitation of  this  calcium  carbonate  can  occur  only  when  the 
supply  of  carbonate  is  in  excess  of  that  which  can  be  con- 
sumed by  living  organisms  and  when  the  conditions  of  tem- 
perature and  pressure  are  such  as  to  expel  the  solvent,  CO2. 
Such  deposits  are  exceptional  rather  than  common.  Accord- 
ing to  Sir  Charles  Lyell  this  condition  exists  in  the  delta  of 
the  Rhone,  and  Bailey  Willis  cites  the  precipitation  of  lime- 


138  BUILDING    STONES   AND    CLAYS 

stones  along  the  margin  of  the  Everglades  in  Florida,  where 
the  inflowing  waters  are  exposed  in  broad,  shallow  sheets  to 
evaporation,  agitation,  and  variations  of  temperature  and 
pressure.  The  calcium  carbonate  is  partly  thrown  down  as 
mud  and  partly  deposited  on  the  underlying  limestones  as  a 
layer  of  rock.  G.  P.  Merrill  states  in  his  "Stones  for  Building 
and  Decoration"  that  the  alternation  of  beds  of  snow-white, 
blue-gray,  greenish  and  almost  black  layers  in  the  Vermont 
marbles  may  perhaps  be  best  explained  on  the  assumption 
that  the  white  layers  were  deposited  from  solution  and  the 
darker  layers  were  beds  of  indurated  shell  mud  and  sand  col- 
ored by  the  organic  impurities  they  contained  at  the  time  they 
were  first  laid  down. 

According  to  I.  C.  Russell  great  masses  of  calcareous  tufa 
have  been  deposited  around  Pyramid  and  Winnemucca  Lakes 
in  Nevada.  When  the  deposits  assume  the  form  of  oolitic 
sand  the  carbonate  is  deposited  around  sand  grains  or  other 
foreign  bodies  as  nuclei.  G.  K.  Gilbert  cites  similar  forma- 
tions around  Great  Salt  Lake  but  only  where  there  is  much 
agitation  of  the  waves.  The  tufa  requires  surf  to  discharge 
the  excess  of  carbon  dioxide  and  deposit  calcium  carbonate. 
A  Rothpletz  attributes  the  formation  of  oolitic  sand  at  Great 
Salt  Lake  to  minute  algae.  F.  Cohn,  through  his  investiga- 
tions of  the  travertine  deposits  of  the  waterfalls  of  Tivoli,  at- 
tributes the  deposition  of  the  calcium  carbonate  to  species  of 
thallophytes,  as  Chara,  and  bryophytes,  as  mosses,  that  are 
capable  of  extracting  carbon  dioxide  and  setting  free  calcium 
carbonate.  When  they  do  this  in  the  presence  of  the  bicar- 
bonate they  deprive  that  salt  of  the  second  molecule  of 
carbonic  acid  and  the  neutral  carbonate  is  thrown  down.  The 
material,  at  first  porous,  is  afterwards  transformed  into  a  com- 
pact rock  by  the  deposition  of  calcite  in  its  interstices. 

W.  Kitchell  attributes  the  formation  of  fresh  water  marls 
in  New  Jersey  to  the  presence  of  algae.  C.  A.  Davis  recognizes 
the  function  of  Chara  in  the  formation  of  certain  marl  deposits 
in  the  lakes  of  Michigan. 

G.  H.  Ashley  and  W.  S.  Blatchley  also  recognized  the  activ- 
ity of  aquatic  plants  in  the  formation  of  the  marl  deposits  of 
the  lakes  in  Indiana.  The  smaller  morainal  lakes  of  central 
New  York  are  rapidly  filling  up  with  marl  deposits.  These 
lakes  are  comparatively  shallow  and  many  of  them  have  their 
waters  constantly  aerated  by  strong  wave-producing  winds. 
The  waters  that  serve  as  feeders  for  the  lakes  flow  over  lime- 
stone areas  and  carry  much  calcium  carbonate  in  solution  into 


LIMESTONES,  DOLOMITES  AND  MARBLES      1.39 

them.  The  lakes  are  rich  in  their  aquatic  plants  which  con- 
sume carbon  dioxide  and  exhale  oxygen.  The  activity  then 
of  algae  may  be  a  potent  influence  in  the  formation  of  the  marl 
deposits.  See  John  M.  Clarke's  paper  on  the  Water-Biscuit  of 
Squaw  Island,  Canandaigua  Lake. 

G.  Steinmann  has  pointed  out  that  albumen  which  is  present 
in  the  organic  parts  of  all  aquatic  plants  may  serve  as  a  pre- 
cipitating agent.  F.  W.  Clarke  suggests  that  albuminoids 
generate  ammonium  carbonate  by  fermentation  and  to  that 
compound  the  precipitation  of  calcium  is  due.  P.  F.  Kendall 
has  shown  that  waters  charged  with  carbon  dioxide  dissolve 
aragonite  far  more  rapidly  than  calcite,  and  that  aragonite 
shells  largely  disappear  while  calcite  organisms  remain  per- 
manently in  fossil  form.  He  also  found  that  calcitic  globi- 
gerina  ooze  appears  in  waters  at  a  depth  of  2,925  fathoms  and 
that  aragonitic  pteropod  shells  practically  disappear  at  depths 
exceeding  1,500  fathoms.  Kendall  concludes  that  as  the  Upper 
Chalk  beds  of  England  carry  only  calcitic  organisms  they  must 
have  been  deposited  in  waters  exceeding  1,500  fathoms  in 
depth.  At  temperatures  exceeding  60  degrees  aragonite  is 
more  apt  to  be  formed  and  that  below  that  temperature  calcite. 
As  coral  life  demands  temperatures  exceeding  68  degrees  ara- 
gonite may  form  and  later  become  calcitized. 

According  to  E.  W.  Skeates  both  aragonite  and  calcite  occur 
in  the  coral  formations.  The  formation  of  a  coralline  lime- 
stone may  be  followed  easily  in  the  fringing  reefs,  barrier 
reefs  and  atolls.  The  order  is  as  follows:  (1)  The  living 
animal,  the  coral  polyp.  (2)  The  dead  animal  with  its  home 
broken  into  fragments  by  the  waves.  (3)  Cementation  of 
these  broken  fragments  by  the  solution  and  redeposition  of  a 
part  of  the  calcium  carbonate.  (4)  The  solid  rock  composed 
of  these  organic  remains.  Such  limestones  may  bear  both 
calcite  and  aragonite,  deposited  directly  from  the  sea  water. 
Both  organic  matter  and  earthy  matter  may  be  present.  S.  P. 
Sharpies  found  in  the  corals  of  the  Gulf  Stream  from  0.28  to 
0.84  per  cent  3CaO,  P2O5.  Dolomitization  of  coralline  lime- 
stones may  be  effected  through  magnesium-bearing  waters. 

The  coquina  of  Florida  and  many  other  sea  beaches  affords 
illustrations  of  limestone  building  from  shells.  These  broken 
fragments  are  cemented  together  by  calcium  carbonate  which 
has  been  deposited  from  solution  in  the  interstices  between 
the  shells.  In  one  instance  as  cited  by  W.  H.  Dall  the  cement 
was  limonite  deposited  by  a  chalybeate  spring.  Quartz  sand 
may  be  commingled  with  the  shell  material.  J.  A.  Howe  in 


140  BUILDING    STONES    AND    CLAYS 

his  "Geology  of  Building  Stones"  cites  brachiopods,  pelecy- 
pods,  g'astropods,  pteropods  and  cephalopods  as  limestone 
builders. 

Crinoidal  limestones  are  formed  from  the  disjointed  frag- 
ments of  the  stems  and  arms  of  crinoids  or  sea  lilies.  The 
cross  sections  of  such  fragments  vary  from  a  small  fraction  of 
an  inch  to  an  inch  or  more  in  diameter.  The  smaller  frag- 
ments have  given  rise  to  the  decorative  stone  known  as 
birdseye  marble.  This  name  has  also  been  applied  to  some 
of  the  coralline  limestones  of  Iowa.  (See  Fig.  126.) 

Oceanic  ooze  may  be  laid  down  on  the  floor  of  the  sea  and 
compressed  into  a  soft  rock  like  the  chalk  cliffs  of  England. 
This  material  may  be  practically  free  from  impurities.  The 
sediments  may  be  rich  in  clay  or  mud  and  produce  a  fine 


Fig.  126. — Cross  section  of  fine  grained  coralline  marble  from  Iowa 
City,  Iowa.  Photo,  by  C.  H.  Richardson. 

grained  argillaceous  limestone  with  every  shade  and  grada- 
tion between  a  calcareous  shale  and  a  pure  limestone.  The 
sediments  may  contain  also  quartz  grains,  largely  calcareous, 
and  produce  a  limestone  that  is  fine  grained  and  hard.  These 
rocks  shade  imperceptibly  from  siliceous  limestones  into  cal- 
careous sandstones.  An  illustration  of  this  transition  is  found 
in  the  limestone  belt  of  central  and  eastern  Vermont. 

Marbleization. — The  marbleization  of  calcium  carbonate,  or 
the  conversion  of  amorphous  carbonate  into  a  crystalline  lime- 
stone or  marble,  may  be  effected  in  a  number  of  ways  as 
shown  by  the  experiments  of  Sir  James  Hall,  G.  Rose,  A. 
Becker,  A.  Johannis,  H.  E.  Boeke  and  H.  Le  Chatelier.  In 
these  experiments  both  temperature  and  pressure  have  been 
widely  varied. 


LIMESTONES,  DOLOMITES  AND  MARBLES      141 

Pressure  alone,  either  long  continued  and  gentle,  or  heavy 
and  of  short  duration,  may  produce  this  change.  It  may  be 
brought  about  by  the  influence  of  heat.  Both  heat  and  pres- 
sure may  work  conjointly  in  effecting  the  marbleization  of 
amorphous  calcium  carbonate.  Actual  fusion  of  the  lime 
carbonate  is  unnecessary.  Water  plays  an  important  part 
in  the  process  for  in  geological  phenomena  its  influence  is 
rarely  excluded.  The  solution  and  redeposition  of  calcium 
carbonate  explains  many  changes  in  the  structure  of  calcar- 
eous rocks. 

Alteration. — Changes  in  limestones  may  be  effected  by  an 
infiltration  of  waters  bearing  silica  in  solution.  By  the  depo- 
sition of  the  silica  the  stone  becomes  silicified.  A  limestone 
may  become  phosphatized  by  the  action  of  meteoric  waters 
flowing  over  beds  of  guano.  It  may  become  gypsumized 
through  the  decomposition  of  inclosed  pyrite  and  the  acid 
sulphates  formed  through  such  decomposition.  The  most 
potent  change  is  effected  by  waters  charged  with  carbon  di- 
oxide. Impure  limestones  yield  a  large  number  of  objection- 
able minerals  through  thermal  metamorphism.  Organic 
matter  furnished  the  necessary  material  for  the  scales  or 
plates  of  graphite  in  the  limestones  of  northern  New  York. 
Silica  provided  the  material  for  the  limpid  crystals  of  quartz 
found  in  the  cavities  of  the  Carrara  marble  of  Italy.  Silica 
may  unite  also  with  a  part  of  the  lime  present,  in  the  formation 
of  such  calcium  silicates  as  wollastonite  and  scapolite.  The 
hydroxides  of  iron  may  yield  hematite  or  through  reduction - 
magnetite.  The  hydroxides  of  aluminum  may  form  corundum 
or  even  ruby,  the  red  gem  variety  of  corundum,  as  in  Burma. 
When  both  silica  and  alumina  are  present  there  occurs  a 
reaction  between  them  and  a  part  of  the  calcium  carbonate 
with  the  formation  of  several  silicates  of  calcium  and  alum- 
inum like  garnet,  vesuvianite,  epidote,  etc.  The  feldspars, 
micas,  amphiboles  and  pyroxenes  may  appear  along  contact 
zones  or  as  inclusions  within  the  metamorphic  limestone  itself. 
Phlogopite  is  characteristic  of  many  limestones  or  marbles 
that  originally  bore  magnesia  and  silica  in  the  presence  of 
iron  compounds.  Magnesia  alone  may  crystallize  out  as  the 
oxide,  periclase.  When  both  magnesia  and  alumina  are 
present  spinel  is  formed.  With  magnesia  and  silica  enstatite 
would  appear.  With  magnesia,  silica  and  iron,  minerals  like 
olivine,  bronzite,  hypersthene,  etc.,  appear.  According  to  J.  F. 
Kemp  the  Adirondack  limestones  were  originally  siliceous 


142  BUILDING    STONES   AND    CLAYS 

dolomites  in  which  the  silica  and  magnesia  segregated  as 
pyroxenes. 

Dolomite. — The  terms  magnesian  limestone,  dolomitic  lime- 
stone and  dolomite  are  used  to  designate  any  calcareous  rock 
containing  a  high  proportion  of  magnesia.  A  limestone  con- 
taining more  than  5  per  cent  MgCCX,  is  often  spoken  of  as 
dolomitic.  The  term  superdolomite  is  often  used  to  denote 
rocks  with  a  large  content  of  magnesium  carbonate  and  a 
small  content  of  calcium  carbonate.  This  term  would  cease 
with  less  than  5  per  cent  CaCO3  and  the  rock  would  pass  into 
magnesite.  In  the  magnesian  rocks  there  is  every  gradation 
possible  between  the  pure  calcite,  CaCO3,  on  the  one  hand  and 
magnesite,  MgCO3,  on  the  other. 

The  true  dolomite  falls  between  these  extremes  where  the 
ratio  approximates  to  that  of  the  mineral  bearing  the  name 
dolomite.  In  this  mineral  the  calcium  carbonate  represents 
54.35  per  cent  and  the  magnesium  carbonate  45.65  per  cent. 
Dolomites  may  occur  either  as  an  alteration  product  within 
a  normal  limestone  or  a  chemically  deposited  rock.  Dolo- 
mitization  may  occur  while  the  fresh  limestone  or  ooze  is  in 
the  sea  in  which  it  is  formed.  This  has  been  observed  in  the 
borings  from  coral  islands.  It  is  called  contemporaneous 
dolomitization.  Subsequent  dolomitization  may  occur  after 
consolidation  and  uplift  of  the  original  material  into  a  land 
mass.  Waters  bearing  in  solution  magnesium  carbonate  as 
they  traverse  limestones  exchange  their  less  soluble  mag- 
nesium carbonate  for  the  more  soluble  calcium  carbonate, 
molecule  by  molecule,  and  thereby  the  rock  mass  graduall)^ 
becomes  dolomitized.  Recent  experiments  show  that  marine 
organisms  secrete  more  magnesium  than  was  formerly 
supposed. 

The  existence  of  dolomites  as  true  chemical  sediments  is 
comparatively  rare.  According  to  J.  A.  Howe  the  Mansfield, 
England,  dolomite  falls  into  this  class.  G.  Leube  cites  a  fresh 
water  dolomite  near  Ulm,  Bavaria.  According  to  T.  Scheerer 
the  oldest  dolomites  were  formed  as  chemical  precipitates. 
The  experiments  of  T.  Sterry  Hunt  also  show  the  possible 
precipitation  of  dolomite. 

Hot  springs  containing  magnesium  carbonate  have  been 
shown  by  J.  E.  Spurr  as  potent  factors  in  the  dolomitization 
of  the  limestone  rocks  around  Aspen,  Colorado.  Where  lime- 
stones are  intruded  by  peridotites  such  dolomitization  may  be 
expected.  In  the  absence  of  the  limestones  the  transition  may 
be  to  a  siliceous  magnesite  as  in  Troy,  Vermont. 


LIMESTONES,  DOLOMITES  AND  MARBLES      143 

According  to  F.  W.  Pfaff  the  products  of  organic  decom- 
position such  as  carbon  dioxide,  ammonium  carbonate,  am- 
monium sulphide  and  hydrogen  sulphide  play  an  important 
part  in  the  process  of  dolomitization.  Carbon  dioxide  acting 
for  a  considerable  period  of  time  upon  the  chlorides  and 
sulphates  of  calcium  and  magnesium  produces  a  double  car- 
bonate of  the  two  bases.  This  condition  is  practically 
paralleled  in  the  concentration  of  sea  water.  Therefore  by 
this  process  dolomite  may  be  formed. 

F.  W.  Clarke  has  suggested  that  algae  may  precipitate 
dolomite  or  the  mixed  carbonates  as  they  do  calcareous  marl. 
It  is  apparent  then  that  dolomite  may  be  formed  by  various 
processes  and  possess  different  modes  of  occurrence. 

Dolomite  Tests. — (1).  Calcite  effervesces  freely  in  the  pres- 
ence of  cold  dilute  HC1.  Dolomite  effervesces  feebly  under 


Fig.  127. — Polished  slab  of  quartzose  marble  from  quarry  of  Hunt- 
ington  and  Clough,  Washington,  Vermont.  Photo,  by  C.  H.  Rich- 
ardson. 

the  same  condition.    Magnesite  similarly  treated  should  suffer 
no  immediate  change. 

(2)  Calcite    when    treated    with    a    solution    of    aluminum 
chloride  and   haematoxylin    (extract  of  logwood)    receives   a 
violet  coating.     Dolomite  under  the  same  condition  remains 
uncolored. 

(3)  Pulverize  a  few  grams  of  rock  suspected  to  be  dolomite. 
Cover  with  water  and  add   a  few  drops  of  phenolphthalein 
solution.     Calcite   gives   a   strong  coloration.      Dolomite   is   but 
slightly  tinted. 

Color. — Limestones,  marbles  and  dolomites  possess  a  wide 
range  of  colors.  They  shade  from  the  pure  white  like  the 
statuary  marble  of  western  Vermont  to  a  jet  black  like  that 


144  BUILDING    STONES   AND    CLAYS 

of  Glens  Falls,  New  York  The  cream,  buff,  brown,  orange 
and  red  tints  are  produced  by  varying  amounts  of  the  oxides 
of  iron,  either  in  a  hydrated  or  anhydrous  condition.  The 
blue  and  some  of  the  gray  colors  are  produced  by  finely 
divided  carbonaceous  matter.  Clayey  matter  often  presents 
a  drab  or  gray  appearance  in  a  limestone.  Iron  disulphide 
in  granules  of  microscopic  size  may  produce  a  gray  color. 
Uncombined  carbon  in  the  larger  amounts  produces  a  black. 

Hardness. — The  hardness  of  the  calcareous  building  stones 
varies  \videly.  Calcite  alone  is  only  3  in  hardness.  Statuary 
marbles  possess  the  same  degree  of  resistance  to  abrasion. 
The  state  of  aggregation  of  the  individual  grains  affects  the 
hardness.  The  coquina  of  Florida,  the  coralline  rocks  of  the 
reefs  of  many  islands  and  the  Caen  marble  of  France  are 
extremely  soft.  The  Bedford  oolite  is  of  medium  hardness. 
The  siliceous  limestones  of  Vermont  are  extremely  hard  and 
cut  to  a  fine  edge.  (See  Fig.  127.) 

Specific  Gravity. — The  specific  gravity  of  limestones  and 
marbles  varies  from  2.7  to  2.9.  Its  weight  per  cubic  foot  is 
a  little  higher  than  that  of  the  average  granite.  With  the 
higher  specific  gravity  the  weight  would  be  181  Ib.  per  cu.  ft. 

Distribution. — Some  form  of  the  calcareous  building  stones 
is  found  in  nearly  all  states  and  practically  in  all  countries 
of  the  world.  Many  of  these  are  used  only  locally  if  at  all. 
Some  have  found  favor  both  at  home  and  abroad.  The  Bed- 
ford, Indiana,  oolitic  limestone,  the  marbles  of  western  Ver- 
mont and  Carrara,  Italy,  fall  into  this  class. 

Age. — The  limestones,  marbles  and  dolomites  do  not  belong 
to  any  particular  age.  They  are  found  in  formations  ranging 
from  the  Archaean  to  the  Tertiary.  Lime  bearing  formations 
are  accumulating  at  the  present  time. 

AMERICAN  LIMESTONES  AND  MARBLES 

The  various  states  producing  calcareous  rocks  will  here  be 
considered  in  alphabetical  order. 

Alabama. — Prof.  W.  F.  Prouty  of  the  University  of  Alabama 
has  kindly  contributed  the  description  of  marbles  from  that 
state. 

The  marbles  of  Alabama  may  be  classified  as  follows, 
viz:  (1)  The  variegated,  red  and  green  varieties  of 
Cambrian  age  from  near  Calera,  Shelby  County.  (2)  The 
pink  semi-crystalline  marble  of  Ordovician  age  from  near 
Pratts  Ferry,  Bibb  County.  (3)  The  gray  semi-crystalline 


LIMESTONES,  DOLOMITES  AND  MARBLES      145 

marble  from  the  sub-Carboniferous  terranes  of  Jackson 
County.  This  marble  very  closely  resembles  the  McMullan 
gray  marble  of  the  Knoxville  district  in  Tennessee.  (4)  The 
black  marble  from  the  carbonaceous  crystalline  limestones  of 
the  Knox  dolomite  formation  in  Calhoun  County.  (5)  The 
onyx  marble  from  near  Childersberg,  Talladega  County.  (6) 
A  white  crystalline  marble,  constituting  the  chief  marble  de- 
posits of  the  state,  which  varies  in  age  apparently  from 
Middle  Cambrian  to  Lower  or  Middle  Ordovician.  (See  Figs. 
128  and  129.) 

The  crystalline  \vhite  marbles  of  Alabama  are  being  rapidly 
developed  at  the  present  time.  These  marbles  are  bringing 
this  state  into  prominence  as  a  marble  producer.  It  has 
however  been  known  for  many  years  that  good  marble  de- 


Fig.  128. — Polished  sample  of  cream  No.  1  marble  from  Gantt's 
quarry,  Alabama.  Photo,  by  C.  H.  Richardson. 

posits  existed  in  this  state.  Small  quarries  were  opened  and 
the  product  used  for  monumental  purposes.  These  monu- 
ments have  given  to  posterity  the  evidence  of  their  long  life 
and  beauty.  These  facts  are  responsible  in  no  small  measure 
for  the  recent  development  of  the  marble  industry  in  Alabama. 
.Monuments  and  tombstones  set  sixty  years  ago  which  have 
been  exposed  to  the  most  extreme  weathering  agencies  of 
that  climate  still  preserve  on  their  surfaces  the  very  finest 
lines  of  carving  and  lettering. 

Texture. — On  the  average  the  Alabama  marbles  are  a  little 
finer  grained  than  the  crystalline  marbles  of  Vermont.  The 
grains  are  also  more  interlocked.  As  a  result  of  this  fact  the 

10 


146  BUILDING    STONES   AND    CLAYS 

Alabama  marbles  have  a  slightly  greater  resistance  to  com- 
pression, a  higher  tensile  strength  and  a  greater  sonorousness. 
Their  translucency  is  unusually  high.  The  chief  impurities 
are  the  light  green  talc  layers,  or  schist  bands,  which  mark 
the  original  bedding  planes.  Some  of  the  beds  of  marble  have 
a  bluish  tone  but  for  the  most  part  the  marketed  product  is 
a  cream  toned  white  with,  or  without,  the  coloring  due  to 
the  presence  of  the  schist  bands.  (See  Figs.  130  and  131.) 

Uses. — Most  of  the  Alabama  Marble  is  sawed  into  thin  slabs 
for  interior  wainscoting  as  it  seems  best  suited  for  this  type 
of  ornamentation.  It  is  also  used  for  all  kinds  of  interior  and 
exterior  construction. 


Fig.  129. — Polished  slab  of  grade  A  marble  from  Gantt's  quarry, 
Alabama.  Photo,  by  C.  H.  Richardson. 

Quarries. — At  the  present  time  there  are  four  quarries  in 
active  operation.  The  main  one  is  located  in  about  the  center 
of  the  marble  field.  It  has  a  large  mill  for  finishing  the 
marble.  The  other  quarries  either  send  their  product  direct 
to  this  mill  for  manufacture  or  sell  the  stone  in  the  block 
form  for  $2.00  per  cu.  ft.,  or  even  more.  Most  of  the  product 
sent  to  New  York  City  is  uncut  on  account  of  the  organized 
labor  there  which  demands  local  finishing  of  the  stone.  (See 
Figs.  132,  133  and  134.) 

Structural  Relations.  —  The  crystalline  marbles  of  Alabama 
occur  in  a  long,  narrow  and  more  or  less  well  defined  valley 
wrhich  is  about  35  miles  in  length  and  from  a  quarter  of  a 
mile  to  a  mile  and  a  half  in  breadth.  The  Ocoee  phyllite 


LIMESTONES,  DOLOMITES  AND  MARBLES      147 

bounds  the  valley  on  the  east.  The  marble  is  separated  from 
the  phyllite  for  the  greater  length  of  the  field  by  a  thrust 
fault.  The  marble  bearing  rocks  in  this  so  called  marble 
valley  are  also  separated  from  the  rocks  on  the  west  side  of 


Fig.  130. — Polished  sample  of  cream  B  marble  from  Gantt's  quarry, 
Alabama.     Photo,  by  C  H.  Richardson. 


Fig.  131. — Polished  slab  of  Pocahontas  marble  from  Gantt's  quarry, 
Alabama.     Photo,  by  C.  H.  Richardson. 

the  area  in  many  places  by  a  fault.  The  marble  beds  have  in 
some  places  a  strike  at  variance  to  the  general  trend  of  the 
valley.  This  is  especially  true  in  the  part  of  the  marble  area 
where  the  marble  bearing  rocks  reach  their  maximum  width. 


148 


BUILDING    STONES   AND    CLAYS 


Through  this  portion  of  the  field  the  marble  bearing  rocks 
constitute  a  fault  block.  The  general  dip  of  the  rocks  is 
always  in  an  easterly  direction  and  at  an  angle  of  about  o() 
degrees.  (See  Fig.  135.) 

Age. — The  age  of  the  marble  beds  is  apparently  different 
in  the  different  portions  of  the  iield.  It  ranges  from  Lower 
Cambrian  to  Ordovician.  There  is  no  definite  paleontological 


Fig.  13:3. — Gantt's  quarry  Alabama,  looking  southwest  and  showing 
a  fold  in  the  rock  which  runs  diagonally  down  the  dip.  Photo,  by 
W.  F.  Prouty. 


evidence    for   assuming   this    age.      The    assumption    is   based 
upon  the  character  of  the  associated  terranes. 

Topography. — There  is  not  a  natural  rock  exposure  through- 
out the  entire  length  of  the  field  save  in  places  where  it  has 
been  faulted  up  or  exposed  in  the  bed  of  the  streams.  The 
topography  of  the  area  is  not  only  interesting  but  it  also  tells 


LIMESTONES,  DOLOMITES  AND  MARBLES      149 

much  concerning  the  character  of  the  stones  below  the  soil 
cover.  The  Ocoee  phyllites  on  the  east  make  bold  hills  which 
descend  rapidly  into  the  marble  area  to  their  west.  The  dolo- 
mites which  often  border  the  marble  area  on  their  west 
occupy  a  slightly  greater  elevation  than  that  of  the  calcitized 
marbles.  In  their  decomposition  they  form  a  soil  of  much 
deeper  red  color.  The  above  statements  also  hold  true  of 
the  dolomites  that  strike  diagonally  across  the  valley. 

Bedding. — In   most   places   the   schistosity  bedding   as   shown 
by   the    schist   lines    is    practically    identical    with    the    bench 


Fig.   133. — View  of  the   sawing   sheds   at   Gantt's   quarry,   Alabama. 
Photo,  by  W,  F.  Prouty. 

joints.  In  other  places  however  the  variation  is  as  much  as 
15  degrees  between  these  two  planes.  This  is  in  part  due 
to  the  drag  folding  of  the  layers  during  lateral  movement. 
The  direction  of  the  movement  that  caused  this  folding  is 
usually  plainly  shown  on  the  slipping  planes  and  may  be  seen 
in  some  cases  in  the  elongation  of  the  crystals  in  that  direction 
as  studied  under  the  microscope. 

Jointing. — A    study    of    the    system    of    jointing    in    Gantt's 


150 


BUILDING    STONES   AND    CLAYS 


quarry  shows  that  there  are  two  distinct  series  of  master 
joints.  One  set  is  at  approximately  45  degrees  to  the  direc- 
tion of  movement.  The  other  set  is  at  right  angles  to  this 
direction.  There  is  also  a  slight  radiation  in  the  direction 
of  the  joints  which  was  apparently  caused  by  the  tortional 
strains  set  up  in  the  rock  during  deformation. 

Quarrying. — The  method  of  quarrying  marble  in  Alabama 
differs  markedly  from  that  followed  in  Vermont  and  Georgia. 
Instead  of  quarrying  on  the  level  floor  the  blocks  are  taken 


Fig.   134. — Sawing   marble  in   the   mill  at   Gantt's   quarry,   Alabama. 
Photo,   by  W.   F.   Prouty. 


out  parallel  to  the  dip.  This  method  is  made  necessary  on 
account  of  the  nature  of  the  dip  of  the  marble  and  the  less 
metamorphosed  and  compacted  nature  of  the  deposits.  Tun- 
nelling is  resorted  to  in  the  Gantt's  quarry.  This  enables 
the  securing  of  a  greater  floor  space  with  less  expenditure 
of  money.  It  also  insures  a  higher  percentage  of  sound 
marble  because  of  its  position  below  the  most  active  zone 
of  weathering.  The  so-called  slicks  or  vertical  joints  which 


LIMESTONES,  DOLOMITES  AND  MARBLES      151 

run  down  the  dip  are  greatly  reduced  in  number  and  often 
almost  absent  in  the  deeper  portions  of  the  quarry.  At  a  depth 
varying  from  75  to  100  feet  a  much  greater  percentage  of  sound 
marble  is  produced  than  at  altitudes  nearer  the  surface.  The 
percentage  of  sound  marble  that  can  be  obtained  in  a  given 
quarry  is  much  smaller  than  it  is  in  Georgia.  In  Alabama  the 
usual  quarry  run  of  sound  marble  is  between  20  and  30  per  cent. 
In  quarries  where  the  joints  run  at  45  degrees  with  the  dip, 
and  the  strike  joints  are  of  secondary  importance,  a  much  higher 
percentage  of  marble  can  be  secured  by  taking  out  the  blocks 
with  the  long  cuts  parallel  to  the  main  or  45  degree  joints.  This 
method  reduces  the  very  wasteful  diagonal  unsoundness  in  the 
blocks.  See  Fig.  136.) 


S  ~f&  Sf^T   of 
Transported 


ostly 


CFLOS  5  -  SECT!  O  N 
GAKTT5    QUARR 


Dip  S.E 


Fig.  135. — Cross  section  of  Gantt's  quarry,  Alabama.     Drawing  by 
W.   F.   Prouty. 


There  are  apparently  several  layers  of  the  marble  inter- 
bedded  with  dolomite  as  in  the  case  of  the  Vermont  deposits. 
In  places  the  dolomite  beds  lens  out  completely.  A  careful 
microscopic  study  of  the  line  of  contact  between  the  dolomite 
beds  and  the  calcite  beds  shows  that  there  are  always,  as  far 
as  seen,  sharp  lines  of  demarcation  between  them.  If  the 
dolomites  are  replacement  products  there  must  have  been  at 
the  time  of  their  replacement  a  very  marked  favoritism  on 
the  part  of  the  magnesian  salts  towards  these  unfortunate 
layers. 


152  BUILDING    STONES   AND    CLAYS 

Thickness. — The  thickness  of  the  deposits  at  the  Gantt's 
quarry  is  clearly  shown  in  Fig.  137. 

Arizona. — Three  distinct  types  of  marbles  are  quarried  in 
Arizona.  They  are  used  for  decorative  purposes.  They  are 
classified  as  (1)  Arizona  Opal  which  shades  from  white 
through  cream  yellow  and  pink.  (2)  Arizona  Pavonazza 
which  shades  from  creamy  white  to  pink  with  strong  black 


Fig.  136. —  Gantt's  quarry,  Alabama,  looking  northeast  into  narrow 
opening.  Photo,  by  W.  F.  Prouty. 

veins.      (3)    Arizona    Pavonazza,    heavy    veined.      Pavonazza 
marbles  are  of  creamy  tint  and  may  not  be  veined. 

Arkansas. — According  to  J.  C.  Branner  the  northern  part 
of  Arkansas  is  covered  with  a  large  belt  of  Ordovician  marbles 
which  occur  in  beds  varying  from  ten  to  one  hundred  feet  in 


LIMESTONES,  DOLOMITES  AND  MARBLES      153 

thickness.  Blocks  of  any  dimension  desired  can  be  obtained. 
The  marbles  shade  from  white  through  pink  to  red.  (See 
Fig.  138.) 

California. — The  limestones  of  California  are  widely  dis- 
tributed throughout  the  state.  No  very  extensive  area  is 
without  them,  yet  the  areas  themselves  are  not  extensive. 
In  thickness  the  beds  are  sometimes  several  hundred  feet. 


Fig.  137. — View  showing  the  initial  stages  of  a  tunnel  in  a  marble 
quarry  in  Alabama.  Two  tunnels  are  now  utilized  to  increase  the 
floor  space  of  this  quarry.  Photo,  by  W.  F.  Prouty. 

They  are  most  prominent  in  Kern,  San  Bernardino,  San  Diego 
and  Santa  Cruz  Counties.  They  were  formed  under  different 
conditions  and  vary  in  texture  and  composition.  They  vary 
in  color  from  white  to  blue.  Some  of  them  are  used  for  build- 
ing stone  and  others  as  decorative  marbles.  The  large  uses 


154 


BUILDING    STONES   AND    CLAYS 


of  the  limestones  proper  are  in  the  beet  sugar  industry,  the 
manufacture  of  lime  and  Portland  cement. 

According  to  T.  C.  Hopkins  marble  is  produced  in  Cali- 
fornia in  Amador,  Inyo,  Riverside,  San  Bernardino  and  Tuol- 
umne  Counties.  Some  of  the  marbles  are  white,  clouded, 
variegated  and  others  are  of  the  onyx  type.  The  beds  in 
Amador  County  vary  in  thickness  from  TOO  to  200  feet.  The 
stone  is  light  gray  and  blue  in  color.  In  Inyo  County  the 
stone  is  a  dolomite.  The  chemical  analysis  gives  calcium 
carbonate  54.25  per  cent,  and  magnesium  carbonate  44.45  per 
cent.  The  marbles  are  white,  yellow,  gray  and  black.  The 
black  is  used  in  floor  tilings.  (See  Fig.  139.) 


Fig.   188. — Red   marble   quarry,    Eureka   Springs,   Arkansas.      Photo, 
by  T.   C.   Hopkins. 


California  Onyx. — The  onyx  marbles  of  California  are  noted 
tor  their  perfect  homogeneity  of  texture,  microcrystalline 
structure,  degree  of  translucency  and  remarkable  beauty.  (See 
Fig.  140.)  Some  of  them  are  deposited  by  hot  springs,  some 
by  cold  springs,  while  others  are  cave  deposits.  The  finest 
and  best  varieties  consist  of  aragonite  while  others  are  calcite. 
The  largest  and  best  deposit  of  onyx  is  found  in  San  Luis 
Obispo  County.  Hopkins  also  states  that  the  onyx  layers  are 


LIMESTONES,  DOLOMITES  AND  MARBLES      155 

irregular  and  vary  in  thickness  from  one  to  thirty  inches.  In 
some  instances  the  layers  are  white,  massive  and  compact  and 
take  a  fine  polish.  Others  are  banded  or  variegated.  In  a  few 
cases  the  seams  are  filled  with  hematite  which  makes  bright 
red  blotches  or  bands  while  other  portions  of  the  stone  are 
banded  with  a  dark  green  color.  The  California  onyx  is  con- 
sidered by  many  to  be  superior  to  any  other  quarried  or  mined 


Fig.   139. — Polished   slab   of  variegated   marble,   Bagdad,   California. 
Photo,  by  C.   H.  Richardson. 


Fig.  140. — Polished  slabs  of  onyx  marble,  San  Luis  Obispo  County, 
California.  Photo,  by  C.  H.  Richardson. 

in  the  world.     Verd  antique  marbles  which  in  reality  are  ser- 
pentines are  also  produced  in  California.     (See  Fig.  141.) 

Colorado. — The  marble  deposits  of  Marble,  Colorado,  are 
100  feet  in  thickness  and  some  six  miles  in  length.  Some  of 
this  stone  is  exceedingly  fine  grained  and  pure  white  in  color. 
It  receives  a  fine  polish  and  competes  with  the  pure  white 


156 


BUILDING    STONES   AND    CLAYS 


statuary  marble  of  West  Rutland,  Vermont,  the  Carrara, 
Italy,  and  those  from  the  Island  of  Paros  in  the  Grecian 
Archipelago.  A  part  of  the  deposit  is  tinted  or  veined  with 
some  hydrated  oxide  of  iron  a  golden  yellow.  This  stone  is 
classified  as  the  golden  vein.  (See  Figs  1-12  and  143.) 

The  author  has  in  his  private  collection  several  samples 
of  most  beautiful  sienna  marbles  from  Colorado.  They  ap- 
pear equal  in  every  respect  to  the  foreign  siennas.  (See 
Fig.  144.) 

Connecticut.  —  The  first  attempt  to  quarry  marble  in  a 
a  systematic  manner  in  the  United  States  was  made  at  Marble- 


Fig.  141. — Verd  antique  marble  quarry,  Victorville,   San  Bernardino 
County,   California.     Photo,  by  T.  C.  Hopkins. 


dale  in  the  town  of  Milford  about  1800.  Although  many 
quarries  have  been  operated  from  time  to  time  they  are  now 
abandoned.  In  the  town  of  Canaan  in  the  same  county  of 
Litchfield  is  found  a  coarse  crystalline  dolomite  that  is  white 
in  color  and  for  many  years  it  was  extensively  quarried  and 
highly  prized  for  structural  purposes.  The  State  House  at 
Hartford,  Connecticut,  was  built  of  this  stone.  It  bears  one 
objectionable  impurity,  tremolite.  The  surfaces  of  many 
buildings  constructed  of  this  stone  have  become  pitted 


LIMESTONES,  DOLOMITES  AND  MARBLES      157 

through  the  loss  of  the  crystals  of  tremolite.  Tremolite  as 
elsewhere  noted  often  changes  its  color  upon  exposure  to  the 
atmosphere.  (See  Fig.  145.) 


Fig.  142. — Polished  slab  of  Colorado  yule  marble,  Marble,  Colorado. 
Photo,  by  C.   H.   Richardson. 


Fig.  143. — Polished  slab  of  gold  vein  marble,  Marble,  Colorado. 
Photo,  by  C.  H.  Richardson. 

Delaware. — A  coarse  white  dolomite  occurs  at  Hockessin, 
New  Castle  County.  It  is  better  suited  for  constructional 
purposes  than  it  is  for  decorative  work. 


158 


BUILDING    STONES   AND    CLAYS 


Florida.  —  This  state  has  been  somewhat  noted  for  its 
peculiar  variety  of  structural  material  known  as  coquina. 
These  cemented  fragments  of  shells  were  used  largely  in  the 
cities  of  St.  Augustine  and  Fort  Marion.  The  best  represent- 
ative of  this  stone  is  found  on  the  Island  of  Anastasia  about 
two  miles  from  St.  Augustine.  Coquina  is  fairly  serviceable 
in  Florida  but  it  would  not  weather  well  in  northern  climates 


Fig.   144. — Polished   slab   of   sienna  marble   from   Colorado, 
by  C.   H.  Richardson. 


Photo. 


Fig.    145. — State    House,    Hartford,    Connecticut.      By    courtesy    of 
S.  H.  Camp. 

on  account  of  its  great  porosity.  At  Key  West  there  occurs 
a  soft  oolitic  limestone  that  has  been  quarried  to  some  extent. 
Georgia. — The  most  important  marble  belt  in  Georgia  lies 
in  the  northern  part  of  the  state  in  Cherokee  and  Pickens 
Counties.  These  marbles  are  of  uniform  texture  but  much 
coarser  than  the  Vermont  marbles.  They  shade  in  color  from 


LIMESTONES,  DOLOMITES  AND  MARBLES      159 

a  pure  white  to  blue  and  variegated.  They  take  a  fine  polish 
and  many  of  them  are  beautiful.  The  pink  variety  is  unique 
as  well  as  beautiful.  In  many  ways  it  is  unlike  any  other 
known  marble  in  this  country.  A  chocolate  red  variety  is 
found  in  Whitfield  County.  Georgia  Marbles  are  practically 
pure  calcite.  They  work  easily  and  owing  to  the  mildness 
of  the  climate  the  quarries  can  be  operated  safely  during  all 
seasons  of  the  year.  The  commercial  names  given  to  these 
marbles  are  Cherokee,  which  is  a  \vhite  calcite ;  Creole,  which 
is  coarse  grained,  black  and  white  mottled ;  Etowah,  which 
is  coarse  grained  and  flesh  colored ;  Silver  Gray  Cherokee, 


Fig.    146. — State    House,    Providence,    Rhode   Island,   built   of  white 
marble  from  Georgia.     Photo,  by  C.  H.  Richardson. 


which  is  in  reality  bluish  gray ;  Southern,  which  is  nearly 
white  with  bluish  gray  markings.  The  State  Capitol  of 
Providence,  R.  I.,  represents  Georgia  white  marble.  (See 
Fig.  146.) 

Idaho. — A  small  amount  of  marble  to  supply  local  demands 
is  quarried  at  Spring  Basin  in  Cassia  County. 

Iowa. — The  State  of  Iowa  furnishes  three  widely  different 
types 'of  marble.  That  furnished  by  Marshall  County  near 


160 


BUILDING    STONES   AND    CLAYS 


Le  Grand  is  popularly  known  as  Iowa  Marble.  It  is  dolomitic 
and  contains  massive  beds  beautifully  veined  with  the  oxides 
of  iron.  The  stone  is  prized  for  decorative  work  but  does  not 
weather  wrell  on  exposure  to  the  atmosphere. 

The  Madrepore  marble  occurs  in  the  vicinity  of  Charles 
City  in  Floyd  County.  It  is  a  dolomitic  rock  of  Devonian 
age.  Certain  strata  furnish  a  coralline  marble  that  is  unique 
and  beautiful.  Stromatopora  fossils  are  abundant.  The 


Fig.  147. — Longitudinal  section  of  a  small  block  of  coralline  marble, 
Iowa  City,  Iowa.     Photo,  by  C.  H.  Richardson. 


Fig.     148. — Cross    section    of    coralline    marble,    Iowa    City,     Iowa. 
Photo,  by  C.   H.   Richardson. 

ground  mass  of  the  stone  is  a  light  drab  but  the  fossils  vary 
in  color  from  a  yellowish  brown  to  a  deep  mahogany.  The 
stone  receives  a  high  polish  and  is  quite  unlike  any  other 
marble  in  the  world. 

The  birdseye  marble  of  Iowa  City  is  not  oolitic  as  might 
be  implied  by  its  commercial  name.     The  coral,  Acervularia 


LIMESTONES,  DOLOMITES  AND  MARBLES      161 

davidsoni,  constitutes  the  main  mass  of  the  stone.  The  corals 
are  perfectly  cemented  together  by  the  deposition  of  calcium 
carbonate  from  solution  so  that  the  stone  receives  a  high 
polish  and  is  well  suited  for  decorative  work,  provided  blocks 
of  desired  dimensions  could  be  obtained.  The  writer  has 
many  polished  samples  of  this  unique  stone  \vhich  are  indeed 
beautiful.  (See  Figs.  147  and  148.) 


Fig.  149. — Lynian  Hall,  Syracuse  University,  Syracuse,  New  York. 
The  base  course  represents  Gouverneur  marble  and  the  central 
courses  oolitic  limestone  from  Bedford,  Indiana.  By  courtesy  of 
Syracuse  University. 

Illinois. — Adams,  Cook,  Kankakee,  Madison  and  Will 
Counties  furnish  a  small  amount  of  limestone  for  structural 
purposes.  Many  of  the  quarries  are  fine  grained,  even  tex- 
tured and  of  light  gray  color. 

11 


162  BUILDING    STONES   AND    CLAYS 

Indiana. — In  this  state  Lawrence,  Munroe  and  Owen  Coun- 
ties are  the  largest  producers  of  limestone.  The  Bedford 
oolite,  named  from  the  quarries  at  Bedford  and  its  oolitic 
structure,  has  justly  won  a  wide  reputation  as  a  desirable 
structural  stone.  The  stone  grades  from  fine  to  medium  in 
texture  and  from  blue  to  buff  in  color.  Sometimes  these 
colors  are  mixed.  The  oolitic  texture  is  generally  pronounced 
but  sometimes  the  rock  is  made  up  of  minute  fossils.  The 
stone  is  extremely  soft  when  quarried  but  hardens  upon  ex- 
posure to  the  atmosphere.  It  works  easily  and  the  finer 
varieties  are  suitable  for  ornamental  work.  The  stone 
in  structural  work  should  always  be  laid  so  that  pressure 
is  at  right  angles  to  the  bedding  planes.  The  Jewish  Syna- 
gogue on  University  Avenue  in  Syracuse  and  the  central 
courses  in  Lyman  Hall  at  Syracuse  University  are  of  this 
stone.  (See  Fig.  149.) 

Kentucky.  —  The  Bowling  Green  oolitic  limestone  has  its 
home  in  Warren  County.  As  its  name  implies  it  closely 
resembles  the  Bedford  oolite  already  described.  It  however 
differs  from  the  Indiana  stone  in  one  respect.  It  may  be  set 
with  safety  in  any  position  in  the  walls  of  a  building.  It 
is  of  fine  even  texture  and  when  freshly  quarried  shows  a 
buff  tint,  which  changes  to  a  light  gray  upon  exposure  to  the 
atmosphere,  due  to  a  loss  of  small  quantities  of  included 
petroleum. 

Maryland. — Two  localities  in  Maryland  are  worthy  of  men- 
tion. The  first  of  these  lies  about  15  miles  north  of  the  city 
of  Baltimore  and  furnishes  the  Cockeysville  marble.  This 
is  quarried  at  Cockeysville  and  Texas.  It  is  an  Ordovician 
dolomite  of  pure  white  color  and  even  texture.  Washington 
Monument  on  the  banks  of  the  Potomac  contains  this  stone. 
It  also  appears  in  the  columns  and  heavy  platforms  of  the 
Capitol  extensions  at  Washington,  D.  C.  (See  Fig.  150.) 

The  other  locality  is  near  Point  of  Rocks,  Frederick  County. 
The  stone  is  a  conglomerate  which  is  sometimes  brecciated. 
The  pebbles  are  quartzose,  the  limestone  fragments  are  dolo- 
mite and  the  whole  imbedded  in  a  calcareous  ground  mass. 
The  stone  is  popularly  known  as  the  Potomac  marble.  This 
stone  was  used  in  the  pillars  in  the  old  Hall  of  Representatives 
in  Washington.  (See  Fig.  151.) 

Massachusetts.  —  The  marble  areas  of  Massachusetts  are 
confined  to  the  Berkshire  Hills  in  the  western  part  of  the 
state.  Massachusetts  marbles  are  of  even  texture,  fine  to 
medium  grained,  and  shade  from  white  to  gray  in  color. 


LIMESTONES,  DOLOMITES  AND  MARBLES      163 

They  are  used  for  structural  and  ornamental  work.  The 
Alford  quarries  produce  monumental  stone  and  the  Lee  quar- 
ries the  structural  stone.  From  the  last  locality  came  the 
marble  for  the  Capitol  extensions  at  Washington.  The  stone 
often  contains  the  objectionable  constituent,  tremolite,  which 
falls  out  on  long  exposure  and  leaves  the  surface  pitted. 

Minnesota. — The  calcareous  building  stones  of  Minnesota 
are  situated  in  the  southern  part  of  the  state  near  Minnesota 
River.  Two  types  are  advertised.  The  Kasota  marble  and 
the  Mankato  marble.  They  are  both  dolomitic  and  receive 
a  polish.  The  interior  of  the  Capitol  building  at  St.  Paul  is 


Fig.    150. — View    of    Beaver    Dam    quarry,    Cockeysville,    Maryland. 
By  courtesy  of  the   Maryland   Geological   Survey. 


from   the   Minnesota   dolomites.     They   are   generally   yellow 
or  yellowish  brown  in  color. 

Missouri. — The  building  stories  commercially  catalogued  as 
marbles  in  this  state  have  a  wide  variety  in  color.  The  pure 
white  crystalline  marble  appears  to  be  wanting.  The  colors 
represented  in  Cape  Giradeau,  Iron  and  Madison  Counties, 
are  gray,  yellow,  pink,  red,  green,  purple  and  variegated.  The 
Monotone  marble  of  Carthage  is  perhaps  the  best  known. 
Many  of  the  above  varieties  are  limestones  rather  than  true 
marbles. 


164 


BUILDING    STONES   AND    CLAYS 


Montana. — Lewis  and  Clark  County  furnishes  a  small 
amount  of  marble  that  is  very  compact,  of  dark  bluish-gray 
color,  and  somewhat  resembles  the  Italian  black  and  gold 
marble  from  the  Spezzia  quarries.  The  stone  is  often 
traversed  by  wavy  chrome-yellow  bands. 

Nevada. — According  to  J.  F.  Newberry  the  workable  beds 
of  limestone  within  the  state  are  situated  in  the  Tempiute 
Mountains  in  the  southern  part  of  the  state.  They  present  a 


Fig.    151. — Potomac    marble,    Point    of    Rocks,    Frederick    County, 
Maryland.     By  courtesy  of  the   Maryland  Geological   Survey. 


wide   variety  in   color  and   texture   and   are   equal   in  beauty 
to  the  best  imported  marbles. 

New  Jersey. — The  State  of  New  Jersey  produces  two  widely 
different  marbles  in  Sussex  and  Warren  Counties.  One  is 
knowrn  as  the  Kittatinny  blue  limestone  w^hich  is  used  as  a 
structural  stone  for  the  local  and  Pennsylvania  market.  The 


LIMESTONES,  DOLOMITES  AND  MARBLES      165 

other  is  known  as  the  "  Rose  Crystal  Marble  "  from  its  pink 
or  rose  color.  These  tinted  crystals  of  calcite  are  associated 
with  black  mica,  a  green  pyroxene  and  a  black  tourmaline. 
The  stone  is  susceptible  of  a  high  polish  and  well  suited  for 
decorative  interior  work. 

New  York. — There  are  four  distinct  belts  of  limestone,  or 
dolomites,  or  marbles,  within  the  state. 

(1)  The  Hudson   River  Belt. — This   field   lies   in  the   south- 
eastern part  of  the  state  and  strikes  in  a  northerly  direction. 
The   beds   are   tilted   to   a   high   angle,    sometimes   reaching  the 
vertical.      The    stone    is    a    dolomite.      The    quarries    of    South 
Dover  produce  the  finest  grained  marbles  of  Westchester  County. 
The   stone   is   white   and   is   used    mainly    for   structural    work. 
The  Tuckahoe  quarries  produce  a  pure  white  marble  of  some- 
what coarser  texture  that  has  been  used  to  a  considerable  extent 
for  building  purposes   in   New   York   City.     The   Metropolitan 
Life  building  in  New  York  is  from  this  stone.     The  gray  color 
of  many  buildings  from  this  stone  is  said  to  be  produced  by  the 
collection  of  dust  upon  its  rough   surfaces.     The   Pleasantville 
quarries  produce  the  coarsest  grained  stone  of  the  three  men- 
tioned.  The  snow  flake  marble  comes  from  a  bed  that  is  about 

•  100  feet  wide  and  snowy  white  in  color. 

The  Becraft  marble  which  is  quarried  on  the  west  side  of 
the  Hudson  River  resembles  some  of  the  Tennessee  marbles. 

(2)  The  Champlain  Belt. — The  southernmost  quarries  in  this 
district  are  situated  at  Glens  Falls,  a  little  to  the  south  of  Lake 
George.     The  stone  is  of  dark  bluish-black  color  and  of  very 
fine  texture.     In  composition  it  is  dolomitic.     The  stone  receives 
a  high   polish   equal   to  the   famous   Irish  black  and   Belgian 
black  marbles  so  often  imported  for  decorative  effect.     Small 
hand  samples  when  polished  are  of  lustrous  black  color,  while 
much  larger  samples  sometimes  show  the  presence  of  small 
white  fossils.     The  same  type  of  black  marble  is  also  quarried 
at  Willsborough  in  Essex  County.    To  the  inexperienced  these 
stones  appear  equal  to  the  famous  Irish  black  marbles. 

A  verd  antique  marble  which  in  reality  belongs  to  the  ser- 
pentine group  of  decorative  stone  is  quarried  at  Port  Henry  in 
the  same  county.  The  marble  consists  of  serpentine  decked  with 
calcite  and  dolomite.  It  is  used  for  interior  work. 

The  Chazy  limestone,  which  often  takes  a  good  polish,  is 
quarried  at  Chazy  and  Plattsburg  in  Clinton  County.  The  stone 
is  often  replete  with  fossils.  The  Lepanto  marble  is  a  fine 
grained  variety  of  gray  color  and  rich  in  white  and  pink  colored 


166 


BUILDING    STONES   AND    CLAYS 


LIMESTONES,  DOLOMITES  AND  MARBLES      167 

fossils  which  afford  a  strong  contrast.  The  French  gray  bears 
larger  fossils  than  the  Lepanto  marble. 

(3)  The  St.  Lawrence  Valley  Belt. — Gouverneur  is  situated 
on  the  western  side  of  the  Adirondack  Mountains  in  St.  Law- 
rence County.  Gouverneur  marble  is  dolomitic  in  composition, 
of  light  gray  color,  of  coarse  texture  and  receives  a  high  polish. 
It  is  used  for  monumental  work,  for  decorative  interior  effect 
ond  for  constructional  purposes.  This  marble  is  of  pre-Lauren- 
tian  age. 

The  Lowville  ("Birdseye")  limestone  is  quarried  at  Lowville 
and  along  the  West  Canada  Creek. 


Fig.  153. — Niagara  limestone,  Rochester,  New  York.  Whitmore, 
Rauber  and  Vicinus  quarry,  North  Goodman  Street.  Base  of  the 
Lockport  and  upper  Rochester  shale.  Photo,  by  H.  L,.  Fairchild. 

(4)  The  Central  Belt. — This  belt  strikes  in  a  westerly  direc- 
tion through  the  central  part  of  the  state.  The  Manlius  lime- 
stone is  of  gray  or  dark  gray  color,  of  fine  even  texture  and 
quarried  extensively  in  the  vicinity  of  Syracuse  for  underpinning 
and  rough-faced  blocks.  The  Onondaga  limestone  is  of  light 
gray  color,  medium  texture  and  quarried  for  structural  purposes. 
The  Hall  of  Languages,  which  was  the  first  building  constructed 
at  Syracuse  University,  represents  this  stone.  A  part  of  the 
Onondaga  limestone  is  sufficiently  crystalline  to  receive  a  good 


168 


BUILDING    STONES   AND    CLAYS 


polish  and  is  therefore  a  marble.  (See  Fig.  152.)  The  Niagara 
limestone  of  Lockport  and  Rochester  is  of  medium  texture,  soft 
gray  color  and  quarried  extensively  for  both  structural  and 
ornamental  work.  (See  Figs.  153  and  154.) 

The  Gasport  limestone,  which  is  crinoidal,  is  quarried  at  Lock- 
port.  The  Trenton  limestones  are  quarried  at  Trenton  Falls. 
Many  buildings  in  Utica  have  been  constructed  from  this  stone. 

North  Carolina. — Marble  deposits  occur  in  this  state  in 
Cherokee,  Madison,  McDowell  and  Swain  Counties.  Their  gen- 
eral strike  is  to  the  northeast.  They  are  from  fine  grained  to 
medium  texture,  and  of  white,  creamy  white,  gray,  green,  pink, 


Fig.  154. — Deccw  limestone,  Rochester,  New  York.  Rauber  and 
Hagaman  quarry,  North  Goodman  Street,  looking  north.  Photo,  by 
H.  L.  Fairchild. 

and  red  colors.  They  may  be  used  for  either  structural  or 
decorative  purposes. 

Ohio. — Limestones  and  dolomites  in  Ohio  are  quarried  to 
some  extent  for  structural  purposes  but  the  major  part  of  the 
production  finds  use  along  the  engineering  lines  of  paving,  flag- 
ging, crushed  stone,  manufacture  of  lime  and  as  fluxing  ma- 
terial. 

Pennsylvania. — According  to  G.  P.  Merrill  marble  quarries 
were  opened  in  Montgomery  County  about  the  time  of  the  Revo- 


LIMESTONES,  DOLOMITES  AND  MARBLES      169 

lutionary  \Yar,  and  up  to  1840  the  stone  was  a  favorite  for 
the  better  class  of  stone  buildings  in  and  about  Philadelphia. 
The  Sarcophagi  of  President  and  Martha  Washington,  at  Mount 
Vernon,  represent  this  stone.  In  Chester  County  at  Avondale 
a  white  dolomitic  marble  is  quarried  for  structural  work.  (See 
Fig-.  155.) 

Tennessee. — More  than  25  counties  in  this  state  are  capable 
of  producing  marbles  which  present  a  wide  variety  in  colors. 
They  are  grayish-\vhite,  olive-green,  brownish-red,  chocolate- 
red  and  pink  in  color.  In  texture  they  are  medium  to  coarse 
grained.  They  are  of  high  compression  strength,  weigh  about 


Fig.    155. — Limestone   quarry   at    Bellefonte,    Pennsylvania.      Photo, 
by  T.    C.    Hopkins. 


180  pounds  to  the  cubic  foot,  take  a  good  polish  and  weather 
well.  The  finer  and  evenly  crystalline  varieties  of  beautiful 
pink  color,  often  traversed  with  narrow,  zigzag  black  bands, 
are  wridely  used  for  wainscoting,  table  tops  and  counters.  The 
chocolate-red  variety  which  is  variegated  and  fossiliferous  is 
a  very  popular  paneling  stone.  Other  uses  of  Tennessee 
marble  are  for  tombstones,  monuments,  switchboards  and 
tiling.  (See  Figs.  156,  157,  158  and  159.) 


170 


BUILDING    STONES   AND    CLAYS 


Vermont. — According  to  C.  H.  Hitchcock  the  first  marble 
quarry  opened  in  Vermont  was  in  Isle  La  Motte  prior  to  the 
Revolution.  H.  M.  Seely  cites  quarries  opened  in  Dorset  in 
1785  by  Isaac  Underbill.  Since  the  early  inception  of  the 
marble  industry  Vermont  has  taken  the  rank  of  first  producer. 
At  times  Vermont  has  furnished  more  than  three-fourths  of 


Fig.     15(3. — Polished    r-lab    of    Xo.     1     Tennessee    marble,    Meadow, 
Tennessee.     Photo,  by  C.   H.   Richardson. 


Fig.  157. — Polished  sample  of  dark  cedar  marble,  Meadow,  Tennes- 
see.    Photo,  by  C.  H.  Richardson. 


the  total  production  of  marble  for  building  purposes  in  the 
United  States  and  four-fifths  of  the  monumental  marbles. 

DISTRIBUTION. — The  marble  belts  of  Vermont  fall  into  six 
districts. 

(1)  The  Rutland  District;  this  belt  has  been  by  far  the 
most  important  producer.  (2)  The  Champlain  District. 


LIMESTONES,  DOLOMITES  AND  MARBLES      171 

(3)  The  Plymouth  District.  (4)  The  Isle  La  Motte  Dis- 
trict. (5)  The  Washington  District.  (0)  The  Roxbury 
District. 

THE  RUTLAND  BELT. — The  Rutland  marbles  are  mainly  sit- 
uated in  Rutland  County  but  quarries  have  been  worked  to  the 
north  in  Addison  County  and  to  the  south  in  Bennington  County. 


Fig.  158. — Polished  slab  of  gray  Tennessee  marble,  Meadow,  Ten- 
nessee.     Photo,  by   C.    H.   Richardson. 


Fig.  159. — Polished  slab  of  champion  pink  marble,  Meadow,  Ten- 
nessee. Photo,  by  C.  H.  Richardson. 

The  beds  of  marble  themselves  vary  widely  in  thickness,  from 
6  feet  to  100  feet  or  even  more.  In  texture  they  are  usually 
fine  grained.  In  color  these  marbles  are  in  part  a  pure  white, 
sometimes  gray,  banded,  variegated,  deep  bluish  black  and 
occasionally  greenish. 

Dorset  Mountain. — On  practically  all  sides  of  this  mountain 
beds  of  good  marbles  have  been  quarried.  The  quarries  of  J.  K. 
Freedly  and  Sons  are  situated  on  the  east  side  of  the  mountain. 


172 


BUILDING    STONES   AND    CLAYS 


The  quarries  are  about  1,000  feet  above  the  valley  and  capped 
by  about  500  feet  of  slate.  The  method  of  quarrying  is  in  part 
open  cut  work  and  in  part  a  room  and  pillar  method.  In  the 
latter  case  large  pillars  of  marble  are  left  to  support  the  roof 
of  slate  that  overlies  the  marble.  Most  of  the  product  of  the 
Freedly  quarries  is  shipped  to  Philadelphia.  On  the  southeast 
side  of  the  same  mountain  are  found  the  so-called  "blue  ledge 


Fig.  160. — View  of  marble  quarry  at  West  Rutland,  Vermont,  show- 
ing dip  of  the  marble  beds.      Photo,  by  C.   H.   Richardson. 


quarries."  It  is  a  very  handsome  bluish  marble  that  is  not  ex- 
tensively worked.  The  Edison  quarries  are  situated  on  the  south- 
west side  of  Dorset  Mountain.  These  quarries  like  some  of  the 
marble  quarries  of  Brandon  and  Pittsford  show  the  peculiarity 
of  the  beds  when  traversed  with  the  channelling  and  gadding 
machines  of  springing  up  from  the  floor  of  the  quarry  and 
tightly  holding  various  tools  in  the  work. 


LIMESTONES,  DOLOMITES  AND  MARBLES      173 

The  quarries  of  the  Dorset  Mountain  Marble  Company 
are  situated  on  the  west  side  of  Dorset  Mountain.  Borings 
have  here  revealed  the  marble  beds  several  hundred  feet 
in  thickness.  The  marble  is  largely  variegated.  Many  abandoned 
quarries  are  found  all  around  the  mountain. 

West  Rutland. — About  25  quarries  in  the  neighborhood  of 
West  Rutland  are  owned  and  operated  by  the  Vermont  Marble 
Company,  which  is  the  largest  marble  company  in  the  world. 


Fig.  1(51. — Interior  view  of  marble  quarry,  West  Rutland,  Vermont, 
showing  dip  of  the  marble  benches.     Photo,  by  C.  H.  Richardson. 

The  marble  beds  lie  on  both  sides  of  a  ridge  that  stretches  from 
the  southern  boundary  of  Rutland  northward  to  the  northern 
boundary  of  Middlebury.  The  beds  vary  from  100  to  200  feet 
in  thickness,  although  important  beds  are  often  much  thinner. 
The  more  important  deposits  lie  on  the  western  side  of  the  ridge 
where  the  angle  of  dip  varies  from  45°  to  80°  to  the  east.  (See 
Figs.  160  and  161.) 


174 


BUILDING    STONES   AND    CLAYS 


b 


LIMESTONES,  DOLOMITES  AND  MARBLES      175 

"Covered  Quarry" — This  quarry  is  300  feet  deep  with  two 
tunnels  some  250  feet  in  length  running  under  the  cliffs.  The 
beds  are  so  free  from  joint  planes  that  blocks  of  any  size  desired 
are  obtainable.  According  to  G.  H.  Perkins  the  texture  is  quite 
uniform  throughout.  The  beds  vary  widely  in  color.  Some 
layers  produce  a  pure  white  statuary  marble  which  G.  P.  Merrill 
says  lacks  the  mellow  waxy  luster  of  its  Italian  prototype.  How- 


Fig.    163. — Marble    quarry,    Proctor,    Vermont.      Photo,    by    C.    H. 
Richardson. 

ever,  the  author  has  seen  two  statuettes  side  by  side,  one  cut 
from  the  Rutland  statuary  marble  and  the  other  from  the  Italian, 
which  practically  every  visitor  declared  came  from  the  same 
quarry.  Other  beds  are  gray,  yellow,  light  brown,  olive,  green, 
blue  and  variegated.  In  one  quarry  there  are  15  beds  that  vary 
in  thickness  from  two  to  ten  feet  and  vary  widely  in  texture, 
color  and  value. 


176  BUILDING    STONES   AND    CLAYS 

The  Eighteenth  Annual  Report  of  the  United  States  Geological 
Survey  furnishes  the  following  data  on  a  geological  section  of 
the  West  Rutland  quarries. 

White  marble  (blue  marble  top) 20  feet 

Green  striped    2   feet 

White  statuary   5-6  feet 

Striped  ornamental    2-6  feet 

White  statuary   3-6  feet 

Layer  partly  green  and  partly  white 4   feet 

Green  and  "Brocadillo".  .  . 2*-3   feet 

Crinkly  siliceous  layer,  half  light,  half  dark 2-3   feet 

Light  and  mottled 4-6  feet 

Green  striped    6  inches 

Wrhite   2  a-  inches 

Half  dark  green  and  half  white 3-6  inches 

Italian  blue   15-20  inches 

Mottled  limestone 

Proctor. — The  town  of  Proctor  formerly  known  as  Sutherland 
Falls,  is  another  important  marble  producer.  The  quarry  floor 
covers  about  three  acres  while  the  marble  walls  rise  over  200 
feet  above  the  floor.  On  the  floor  the  beds  lie  in  nearly  a  hori- 
zontal position  with  some  evidence  of  an  anticlinal  arrangement. 
The  colors  range  from  nearly  white  to  dark  gray.  (See  Figs. 
162  and  163.) 

"Mourning  Vein." — The  marble  of  this  quarry  is  of  very  fine 
texture  with  numerous  wavy  and  almost  black  markings.  H.  M. 
Seely  says  "That  it  would  be  interesting  to  know  the  origin  of 
these  mourning  marbles,  in  which  the  white  and  black  are  so  con- 
spicuously mingled.  The  material  giving  the  black  appearance  is 
undoubtedly  carbon,  and  probably  in  character  approaching  the 
graphite  which  marks  the  coarsely  crystalline  limestones  of  the 
Adirondack  region.  When  freely  exposed  to  a  high  heat  the 
dark  color  disappears,  leaving  a  white  line.  The  conjecture 
might  be  ventured  that  the  rock  was  originally  of  different  chem- 
ical composition  in  the  different  parts.  In  the  white  the  oxidation 
of  the  carbon  was  complete  during  metamorphism,  while  in  the 
dark  the  oxidation  was  interfered  with.  A  second  theory  would 
be  that  during  the  metamorphism  the  particles  of  carbon  moved 
together  and  became  aggregated  as  in  the  Adirondack  marble." 
The  first  theory  is  supported  by  an  actual  difference  in  chemical 
composition  as  the  dark  portions  carry  insoluble  siliceous 
minerals  that  are  absent  in  the  white  portions. 

Pittsford. — There  are  three  marble  beds  in  Pittsford,  which 


LIMESTONES,  DOLOMITES  AND  MARBLES      177 

strike  north  and  south,  and  vary  from  200  to  400  feet  in  width. 
The  marbles  vary  from  white  to  a  dark  blue.  The  quarries  now 
in  operation  produce  the  latter  variety. 

Brandon. — About  half  a  mile  south  of  Brandon  station  are 
situated  the  long  narrow  beds  of  Brandon  Italian  marble.  The 
beds  are  about  8  feet  thick  and  channelling  machines  are  used 
to  cut  the  stone.  The  Bardillo  quarries  are  situated  about  two 
cdid  one-half  miles  southwest  of  Brandon  station.  These 
quarries  produce  a  unique  marble  that  is  strongly  marked  with 
narrow  veins  that  traverse  the  stone  in  zigzag  lines  with  some 
regularity.  The  colors  shade  from  light  to  dark  gray.  (See  Fig. 
164.) 

Age. — The  age  of  the  marbles  of  this  most  important  marble 
belt  of  America  is  Ordovician.  Some  of  the  lower  beds  of  the 


Fig.  164. — Polished  slab  of  Italian  marble,  Brandon,  Vermont. 
Photo,  by  C.  H.  Richardson. 

West  Rutland  quarries  may  yet  be  proven  older  than  the  Chazy 
division  of  the  Ordovician  and  the  uppermost  beds  may  be 
younger  than  the  Chazy.  In  the  main  they  are  Chazy.  The 
dolomite  beds  are  probably  of  Cambrian  age. 

The  Vermont  Marble  Company,  which  operates  the  great 
majority  of  the  quarries  in  the  Eolian  or  Rutland  district  has 
kindly  furnished  the  following  list  of  varieties  with  their  char- 
acteristic trade  names.  The  list  includes  seven  marbles  from 
the  Winooski  district  and  one  from  the  Roxbury  district. 

Albertson,  extra  dark. — This  marble  has  long  been  known  as 
the  Esperanza.  It  is  one  of  the  darkest  of  the  Vermont  marbles. 

12 


178  BUILDING    STONES   AND    CLAYS 

The  ground  mass  is  thickly  covered  by  darker  veins  in  many 
cases  more  or  less  confluent.  The  quarries  are  at  West  Rutland. 
American  Pai'onazzo. — The  ground  is  a  delicately  shaded 
creamy  white  or  light  yellow.  The  stone  is  veined  with  many 
shades  varying  from  light  to  almost  black.  The  quarries  are  at 
West  Rutland. 

American  Yellow  Pavonazzo. — The  ground  is  a  light  yellow 

or  yellow   salmon.     The   green   clouds   are   verv  irregular    and 

sinuous.     The  contrast  is  strong.     The  quarries  are    at    West 
Rutland.      (See  Fig.  165.) 


J 


Fig.  165. — Polished  slab  of  American  pavonazzo  marble,  West  Rut- 
land, Vermont.  Photo,  by  C.  H.  Richardson. 

Avenatto. — This  marble  has  a  very  light  ground  with  many 
light  brown  veins  fading  to  a  smoke  brown.  The  veins  are  very 
irregular  and  extend  in  different  directions.  The  stone  is  quarried 
at  Florence. 

Best  Light  Cloud  Rutland. — At  a  distance  this  stone  appears 
white.  It  contains  a  very  small  amount  of  coloring  matter.  The 
stone  is  quarried  at  West  Rutland. 

Brandon  Italian. — As  the  name  implies,  this  marble  somewhat 
closely  resembles  the  ordinary  imported  Italian  marble.  The 


LIMESTONES,  DOLOMITES  AND  MARBLES      179 

ground  is  white  but  more  or  less  thickly  veined  with  black  or 
bluish  lines,  or  spots,  or  blotches.  The  quarries  are  at  Brandon. 
(See  Fig.  166.) 

Brocadillo. — This  is  a  green  marble.  The  ground  is  a  greenish 
white  in  which  there  are  veins  and  clouds  of  varying  shades  of 
green.  The  quarries  are  at  West  Rutland. 

Cipollino. — The  general  color  of  this  marble  is  a  slightly 
yellowish  green.  Three  varieties  are  recognized,  light,  medium 
and  dark.  The  stone  is  obtained  from  the  Westland  quarry  at 
West  Rutland. 


i  tiiiiiijiJiiiij 


Fig.  166. — Sarcophagus  constructed  by  the  Vermont  Marble  Com- 
pany. By  courtesy  of  the  Vermont  Marble  Company. 

Dark  Florence. — The  bluish  ground  of  this  marble  is  abund- 
antly veined  by  regular  and  fairly  straight  lines,  or  bands,  which 
are  often  confluent.  The  quarries  are  at  Florence. 

Dark  Vein  True  Blue. — This  stone  is  one  of  the  darkest  of  the 
blue  marbles  but  lighter  than  the  Albertson.  The  quarries  are 
at  West  Rutland.  (See  Fig.  167.) 

Dorset  Green  Bed. — The  ground  of  this  marble  is  white  or 
greenish  with  streaks  and  bands  of  varying  shades  of  green.  The 
quarries  are  at  Dorset.  . 

Dorset  A. — The  ground  of  this  marble  is  almost  white  with  a 
slight  yellowish  tint  clouded  by  faint  greenish  or  olive  patches. 
The  quarries  are  at  Dorset. 


180  BUILDING    STONES   AND    CLAYS 

Dorset  B. — The  ground  is  nearly  white  with  irregular  bands 
of  creamy  white  alternating  or  blending  with  streaks  or  clouds 
of  greenish  shades.  The  quarries  are  at  Dorset. 

Dove  Blue  Rutland. — The  stone  is  of  gray-blue  color.  Some- 
times it  is  of  Quaker  drab  color.  This  bed  carries  the  well 
known  fossil,  Maclurea  magna,  which  fixes  definitely  the  age  of 
the  formation.  The  quarries  are  at  West  Rutland. 

Esperanza. — The  ground  of  this  stone  is  a  dark  bluish  gray 
and  through  this  there  are  lines  and  veins  of  still  darker  shades 


Fig.  167. — Polished  slab  of  true  blue  marble,  West  Rutland,  Ver- 
mont, showing  faults.  By  courtesy  of  the  Vermont  Marble  Company. 

of  the  same  color  and  others  are  nearly  black.  The  quarries  are 
at  West  Rutland. 

Fisk  Black. — Some  of  the  layers  of  this  marble  are  so  dark  a 
grade  that  when  they  are  polished  they  appear  a  jet  black.  The 
quarries  are  on  Isle  la  Motte. 

Florentine  Blue. — This  marble  is  of  medium  tone,  lighter  than 
most  of  the  blue  marbles  and  darker  than  others.  When  polished 
it  is  of  dark  dove  shade.  The  quarries  are  at  Pittsford. 


LIMESTONES,  DOLOMITES  AND  MARBLES      181 


Fig.    168. — American    eagle    cut   from   Vermont  white   marble.      By 
courtesy  of  the  Vermont  Marble  Company. 


182  BUILDING    STONES   AND    CLAYS 

Jasper. — All  of  the  varieties  are  red  or  reddish  in  color  with  a 
good  deal  of  white  calcite  and  quartz.  The  jasper  marbles  receive 
a  high  polish  and  are  very  lasting.  The  quarries  are  at  Swanton. 

Light  Rutland  Italian. — This  marble  has  large  areas  of  fairly 
white  color  with  a  few  clouds  shading  out  into  the  white  ground. 
It  has  much  the  appearance  of  the  common  Italian  marbles.  The 
quarries  are  at  West  Rutland.  (See  Fig.  168.) 

Light  Sutherland  Falls. — This  marble  is  nearly  pure  white  but 
in  the  ground  there  are  distributed  numerous  and  quite  distinct 
dark  bluish  veins.  The  quarries  are  at  Proctor. 


Fig.  169. — Polished  slab  of  listavena  marble,  West  Rutland,  Ver- 
mont. Photo,  by  C.  H.  Richardson. 

Listavena. — This  is  a  veined  marble  and  one  of  the  best  for 
interior  work.  The  white  bands  alternate  with  shades  of  green 
or  olive.  The  quarries  are  at  West  Rutland.  See  Fig.  169.) 

Lcvido. — The  ground  of  this  marble  is  a  light  bluish  gray  with 
numerous  veins,  lines  and  blotches  of  a  much  darker  hue.  The 
quarries  are  at  West  Rutland.  (See  Fig.  170.) 

Lyonnaise. — The  red  color  in  this  marble  is  darker  than  that 
in  the  Jasper.  The  veins  are  dark  and  lighter  shades  of  red. 
Some  of  the  veins  are  white.  The  quarries  are  at  Swanton.  (See 
Fig.  171.) 


LIMESTONES,  DOLOMITES  AND  MARBLES      183 

Marine  Vcnoso. — The  confluent  veins  and  bands  of  this  marble 
form  bold  masses  of  shades  of  green,  darker  and  lighter,  with 
broad  wavy  bands  of  white  and  sometimes  pink  colors.  The 
stone  closely  resembles  some  of  the  Georgia  marbles.  The 
quarries  are  at  West  Rutland. 

Moss  Vein. — In  this  marble  the  two  colors,  a  dark  gray  and 
a  white,  are  peculiarly  intermingled.  The  darker  shades  pre- 
dominate. The  quarries  are  at  Dorset. 

Olive. — As  the  name  implies  the  ground  of  this  marble  is  a 


Fig.  170. — Polished  slab  of  livido  marble,  West  Rutland,  Vermont. 
Photo,  by  C.  H.  Richardson. 

drab  or  olive  drab.  In  many  pieces  of  the  marble  there  are  vary- 
ing shades  of  red,  mostly  quite  light.  The  quarries  are  at 
S  wanton. 

Oriental. — This  peculiar  marble  presents  an  intermingling  of 
red,  brownish  red,  purplish  red  and  clear  white  colors.  It  is  one 
of  the  finest  and  most  beautiful  of  the  Vermont  marbles.  The 
quarries  are  at  Malletts  Bay.  (See  Fig.  172.) 

Pink  Listavena. — This  marble  is  delicately  shaded  in  the  ex- 
quisite pink  ground  and  the  equally  shaded  greenish  veins  and 
bands.  The  quarries  are  at  West  Rutland. 

Riverside. — This  is  a  light  pearl  white  variety.    There  are  some 


18-4 


BUILDING    STONES   AND    CLAYS 


bluish  veins,  spots  and  bands.  The  usual  waste  found  in  most 
quarry  openings  is  absent  here.  The  quarries  are  between 
Proctor  and  Rutland. 

Royal  Red. — This  stone  is  for  the  most  part  a  deep  Indian  red, 
with  a  blending  of  dark  and  rich  shades.  The  quarries  are  at 
Swanton.  (See  Fig.  173.) 

Riiblo. — This  marble  is  a  light  salmon  pink  with  softly  shaded 
light  green  or  greenish  veins.  The  quarries  are  at  West  Rutland. 

Rutland  Building. — This  is  one  of  the  more  common  white 
marbles  used  for  building  purposes.  The  quarries  are  at  West 
Rutland. 


Fig.  171. — Polished  slab  of  lyonnaise  marble,  Swanton,  Vermont. 
Photo,  by  C.  H.  Richardson. 

Special  Rutland  Italian. — This  stone  is  less  clouded  and  more 
distinctly  veined  than  the  Light  Rutland  Italian  marble.  The 
quarries  are  at  West  Rutland. 

Standard  Green. — The  green  shades  are  the  most  prominent 
with  smaller  areas  of  white,  pink  and  very  light  bluish  shades. 
The  quarries  are  at  West  Rutland. 

Swanton  Dove. — This  marble  is  a  drab  or  bluish  gray  varied 
by  pure  veins,  wrhite  spots  and  blotches.  The  quarries  are  at 
Swanton. 


LIMESTONES,  DOLOMITES  AND  MARBLES     '185 

True  Blue. — This  marble  has  a  medium  ground  which  is 
crossed  by  dark  to  black  bedding  planes.  The  quarries  are  at 
West  Rutland. 

Vcrd  Antique. — This  stone  is  a  serpentine.  It  will  be  described 
more  fully  in  Chapter  VII.  It  is  a  marble  only  in  a  commercial 
sense.  The  rock  is  of  dark  purplish  or  greenish  color  in  the  mass 
and  plentifully  veined  with  dolomite.  The  quarries  are  at  Rox- 
bury.  (See  Fig.  174.) 

Verdoso. — In  this  marble  the  shades  vary  from  apple  green  to 
dark  and  even  black.  The  quarries  are  at  West  Rutland.  (See 
Fig.  175.) 


Fig.  172. — Polished  slab  of  oriental  marble,  Malletts  Bay,  Vermont. 
Photo,  by  C.  H.  Richardson. 

Vert  de  Mer. — The  general  tone  of  this  marble  is  light  with  a 
few  small  and  dark  veins.  The  peculiar  mottled  effect  causes 
the  surface  of  the  stone  to  appear  covered  with  slightly  rippling 
water.  The  quarries  are  at  West  Rutland. 

Westland  Cream. — This  marble  was  formerly  called  Rosaro. 
The  most  common  tone  is  a  light  yellow  with  more  or  less  of  a 
salmon  tone.  The  quarries  are  at  West  Rutland. 

THE:  WINOOSKI  DISTRICT. — This  belt  of  calcareous  rocks  ex- 
tends southward  along  the  eastern  shore  of  Lake  Champlain 


186  BUILDING    STONES   AND    CLAYS 

from  the  International  boundary  on  the  north  to  Shoreham.  The 
belt  is  narrow  and  practically  parallel  with  the  Champlain  coast 
line.  The  marbles  are  commercially  known  as  the  Champlain 
marbles.  The  thickness  of  these  beds  will  be  seen  in  the  geo- 
logical section  cited  a  little  later  in  this  work. 

Origin. — The  origin  of  these  unique  marbles  differs  so  widely 
from  the  true  metamorphic  marbles  of  \Yest  Rutland  that  it 
deserves  special  mention.  The}'  represent  beds  of  siliceous 
sediments,  highly  calcareous,  which  are  now  substantially  in  the 
same  condition  as  when  they  were  originally  deposited.  They 
have  never  suffered  the  characteristic  metamorphism  of  the  true 
marbles.  In  this  respect  they  differ  widely  from  all  other  marbles 
of  the  state  save  the  marbles  of  Isle  La  Motte  which  in  reality  are 
limestones. 


Fig.  173. — Polished  slab  of  royal  red  marble,  Swanton,  Vermont. 
Photo,  by  C.  H.  Richardson. 

Color. — The  color  is  chiefly  some  shade  of  red.  Light  red, 
dark  red,  yellowish  red,  pink,  reddish  brown,  olive,  light  green 
and  even  white  marbles  are  encountered.  In  texture  these 
marbles  are  fine  grained  to  medium  and  very  hard. 

Composition. — In  composition  these  marbles  may  be  classified 
as  siliceous  dolomites.  The  calcium  carbonate  ranges  from  30 
to  40  per  cent ;  the  magnesium  carbonate  ranges  approximately 
the  same  ;  the  silica  from  10  per  cent  upwards,  while  iron  and 
alumina  are  present  in  smaller  proportions.  Specimens  taken 
for  analysis  from  different  places  in  the  same  quarry,  or  from 
different  quarries  would  yield  different  results.  The  old  red 
sandrock,  of  which  these  beds  form  a  part,  consists  of  sand  held 
together  by  a  calcareous  and  ferruginous  cement.  Some  of  the 


LIMESTONES,  DOLOMITES  AND  MARBLES      187 

layers  appear  quite  different  from  the  old  red  sandrock,  while 
others  pass  into  it  by  insensible  gradations.  The  marble  beds 
themselves  appear  just  north  of  the  city  of  Burlington  and  ex- 
tend in  a  northerly  direction  through  St.  Albans  to  Swanton. 

The  Barney  Marble  Company,  now  a  part  of  the  Vermont 
Marble  Company,  operates  the  great  majority  of  the  quarries  in 
this  district.  More  than  30  varieties  are  produced.  The  stone 
is  far  better  suited  for  decorative  interior  work  than  it  is  for 
monumental  or  structural  purposes,  as  the  stone  exposed  to  the 
weather,  fades  to  a  somewhat  limited  extent.  The  stone  when 
protected  from  the  inclemency  of  the  weather  is  always  perma- 


Fig.  174. — Polished  slab  of  Verd  antique  marble,  Roxbury,  Ver- 
mont. Photo,  by  C.  H.  Richardson. 

nent  in  color.  This  stone  can  be  seen  in  the  wainscoting  in  the 
corridors  in  the  Capitol  at  Albany,  N.  Y.,  and  in  the  Astor 
library  in  New  York  City. 

The  possibility  of  the  large  number  of  varieties  obtainable  in 
this  belt  is  explained  by  the  fact  that  the  upper  and  lower  sur- 
faces vary  greatly  in  the  same  slab.  Variations  also  are  produced 
by  cutting  the  stone  at  one  time  parallel  with  the  planes  of 
sedimentation  and  at  another  time  transverse  to  these  planes. 
In  fact,  any  deviation  in  cutting  gives  different  results  in  color 
or  varieties  of  color. 


188  BUILDING    STONES    AND    CLAYS 

A  breccia  marble  containing  fragments  of  broken  material 
ranging  in  size  from  a  small  fraction  of  an  inch  to  many  inches, 
enclosed  in  a  dark  red  paste,  furnishes  one  of  the  handsomest 
varieties.  The  angularity  of  some  fragments  is  perfect,  for  the 
material  appears  to  have  been  one  larger  piece  when  first  held 
in  the  paste  and  subsequently  broken.  In  such  instances  the 
fractured  parts  correspond  perfectly  with  each  other.  In  other 
cases  the  structure  conforms  to  that  of  an  inter-formational  con- 
glomerate. Here  the  angularity  of  the  fragments  is  lost  for  the 
material  was  well  worked  before  cementation  became  complete. 

The  following  geological  section  (reading  down)  wras  worked 
out  by  W.  E.  Logan  and  modified  by  G.  H.  Perkins. 


Fig.    175. — Polished    slab    of    Verdosa    marble,    West    Rutland,    Ver- 
mont.    Photo,  by  C.  H.  Richardson. 

White  and  red  dolomite  (Winooski  marble)  with  sandy 
layers ;  some  of  the  strata  are  mottled,  rose  red  and 
white,  and  a  few  are  brick  red  or  Indian  red 370  feet 

Gray  argillaceous  limestone,  partly  magnesian 110  feet 

Buff   sandy    dolomite 40  feet 

Dark   gray   and   bluish   black    slate,    partly    magnesian, 

with  thin  bands  of  sandv  dolomite.  .  .  .    130  feet 


LIMESTONES,  DOLOMITES  AND  MARBLES      189 

Bands  of  bluish  mottled  dolomite,  mixed  with  patches 
of  gray  pure  limestone  and  gray  dolomite  and  bands 

of  gray  micaceous  flagstone 60  feet 

Light  gray  more  or  less  dolomitic  sandstones,  some  of 
which  are  fine  grained,  others  are  fine  conglomerates. 
These  are  interstratiried  with  bands  of  a  white  sand- 
stone    630  feet 

Bluish  thin  bedded  argillaceous  flagstones  and  slates.  .  .      60  feet 

Bluish  and  yellow  mottled  dolomite 120  feet 

Yellowish  and  yellowish  gray  sandy  dolomite 600  feet 

To  which  Logan  adds  in  Canada 

Buff  and  whitish  sandy  dolomite,  holding  a  great 
amount  of  black  and  gray  chert  in  irregular  frag- 
ments of  various  sizes  up  to  a  foot  in  length  and  six 
inches  wide  (thickness  estimated) 790  feet 


2910  feet 


Fig.  176. — Polished  slab  of  quartzose  marble  from  R.  F.  Richardson 
quarry,  Washington,  Vermont.  Photo,  by  C.  H.  Richardson. 

Age. — The  Champlain  marbles  are  older  than  those  of  West 
Rutland.  The  red  sandrock  which  carries  the  beds  of  widely 
variegated  marbles  is  specifically  recognized  as  Lower  Cambrian, 
from  the  presence  of  its  fossil  content. 

TH£  PLYMOUTH  BELT. — The  highly  variegated  marble  of 
Plymouth  covers  a  large  part  of  the  township  bearing  that  name. 
The  beds  are  about  250  feet  above  Plymouth  Pond  and  some 
six  miles  from  the  railroad  station  at  Ludlow.  The  marble 
beds  are  associated  with  talcose  schists  and  strike  north  10 
degrees  west  with  dip  60  degrees  to  the  east.  T.  N.  Dale 
considers  these  marbles  of  Cambrian  age. 


190  BUILDING    STONES   AND    CLAYS 

Composition. — The  marble  is  practically  a  pure  dolomite,  as 
will  be  shown  in  the  analyses  of  marbles  given  for  reference.  It 
is  of  fine  grain,  even  texture,  of  white  and  variegated  colors, 
often  banded,  splits  well  in  all  directions  and  strongly  resists 
atmospheric  influences.  The  distance  from  the  railroad  does  not 
permit  this  decorative  marble  to  actively  compete  with  the  Rut- 
land and  Champlain  marbles. 

ISLE  LA  MOTTE  BELT. — On  Isle  La  Motte  in  Lake  Champlain 
there  are  extensive  beds  of  limestone,  some  of  which  are  suscep- 
tible of  a  high  polish.  They  are  of  fine  even  texture  and  in  color 


Fig.  177. — Blocks  of  quartzose  marble  showing  character  of  freshly 
broken  surface.  The  two  larger  pieces  are  Washington  marble  and 
the  smaller  one  is  Waits  River  marble.  Photo,  by  C.  H.  Richardson. 

gray  to  black.  The  black  varieties  become  at  times  mottled  in 
appearance  due  to  numerous  small  fossil  fragments.  The  black 
color  is  due  to  the  presence  of  uncombined  carbon.  Many 
samples  of  this  variety  take  a  polish  equal  to  that  of  the  famous 
Irish  and  Belgian  black  marbles.  The  beds  lie  in  a  nearly  hori- 
zontal position  and  vary  from  two  to  ten  feet  in  thickness.  The 
entire  limestone  beds  represent  about  thirty  feet  of  rocks.  The 
stone  from  the  Goodsell  and  Fleury  quarries  is  mainly  gray  in 
color  and  placed  on  the  markets  as  "French  gray"  marble.  The 


LIMESTONES,  DOLOMITES  AND  MARBLES      191 

stone  from  the  Fisk  quarries  is  mainly  black  and  sold  as  "Fisk 
black"  marble.  The  stone  is  in  a  large  demand  for  bridge  piers, 
foundation  work  and  decorative  interior  work.  These  limestones 
represent  a  deep  stillwater  deposit  that  since  deposition  has  been 
but  slightly  disturbed. 

Age. — The  age  of  the  gray  limestones  is  lower  Chazy  and  of 


Fig.  178. — Monument  cut  from  Washington  marble,  Washington, 
Vermont,  showing  marked  contrast  between  the  hammered  and  pol- 
ished surfaces.  Photo,  by  C.  H.  Richardson. 

the  black  middle  Chazy,  which  places  them  both  in  the  Chazy 
division  of  the  Ordovician. 

THE  WASHINGTON  DISTRICT. — This  district  is  named  from  the 
township  of  Washington  in  Orange  County,  where  several 
quarries  have  been  opened  and  abandoned.  The  beds  here  lie  in 
a  nearly  horizontal  position  with  a  pitch  of  three  to  five  degrees 
to  the  north  and  a  strike  of  north  20  degrees  west.  Some  of  the 


192 


BUILDING    STONES   AND    CLAYS 


sheets  are  from  eight  to  ten  feet  in  thickness  and  from  ten  to 
one  hundred  feet  in  length.  The  stone  hammers  white  and  tt  e 
polished  letters  are  legible  to  a  greater  distance  than  the 
letters  on  any  known  granite.  (The  author  has  personally 
made  over  1,500  of  these  tests.)  The  stone  cuts  to  a  fine  edge 
and  takes  a  high  polish.  The  polished  surface,  which  is  uni- 
formly dark  gray,  is  permanent  when  not  exposed  to  the 
corrosive  agents  of  the  atmosphere.  The  stone  is  used  for 
underpinning  and  monumental  work.  (See  Figs.  170,  177  and 

]rvo   \ 
<  o. ) 

Waits  Rrc'cr. — The  marble  here  instead  of  being  uniformly 
dark  gray  like  most  of  the  Washington  marble,  is  plicated  or 
beautifully  banded  and  mottled  in  appearance.  The  stone  has 
been  quarried  and  used  to  some  extent  for  monumental  work. 


Fig.  179. — Polished  block  of  Waits  River  marble,  Waits  Riverr 
Vermont,  from  H.  C.  Richardson  quarry.  The  sample  was  polished 
in  1893  and  photographed  in  1916.  Photo,  by  C.  H.  Richardson. 

It  is  better  suited  for  decorative  interior  work  than  for  structural 
purposes.  (See  Fig.  179.) 

The  belt  of  limestone  in  which  these  two  marbles  fall  stretches 
in  a  northeasterly  direction  across  the  entire  state  and  reaches- 
a  maximum  width  of  over  thirty  miles.  Some  beds  are  known 
to  be  over  200  feet  in  thickness. 

Quarries  of  these  quartzose  marbles  can  be  opened  in  Cale- 
donia, Orange,  Orleans,  Washington  and  Windsor  Counties. 
These  deposits  are  best  catalogued  as  marble  reserves.  (See 
Fig.  180.) 

Origin. — These  limestones  represent  a  deposition  of  siliceous 
sediments  that  were  largely  calcareous.  They  carry  from  25  to- 


LIMESTONES,  DOLOMITES  AND  MARBLES      193 

35  per  cent  of  silica,  from  50  to  60  per  cent  of  calcium  car- 
bonate and  less  than  5  per  cent  of  magnesium  carbonate.  The 
beds  of  limestone  pass  sometimes  by  insensible  gradations  into 
a  calcareous  sandstone. 

Age. — The  age  of  these  marbles,  based  upon  paleontological 
evidence,  is  Ordovician. 

Rhodonite. — This  rock  occurs  at  Waits  River,  Vermont,  in 
masses  of  sufficient  size  to  be  of  commercial  significance.  It  is 
susceptible  of  a  high  polish.  It  is  a  silicate  of  manganese,  and 
may  be  catalogued  as  a  minor  decorative  stone.  (See  Fig. 
181.) 

THE:  ROXBURY  DISTRICT. — This  little  district  is  situated  on  the 
height  of  land  along  the  Central  Vermont  railroad  between 
Montpelier,  the  Capital  of  the  state,  and  White  River  Junction. 


Fig.  180. — Thin  slab  of  unpolished  quartzose  marble  from  St.  Johns- 
bury,  Vermont.  Photo,  by  C.  H.  Richardson. 

The  place  where  the  quarries  were  opened  by  the  American 
Verde  Antique  Company  is  about  eighty  rods  from  the  Roxbury 
Station. 

These  properties  were  worked  for  many  years  by  the  Barney 
Marble  Company  of  S wanton,  Vermont.  They  are  now  owned 
and  operated  by  the  Vermont  Marble  Company  of  Proctor,  Vt. 
The  Barney  Marble  Company,  however,  is  permitted  to  retain 
its  name. 

Mineral  Composition. — This  stone,  strictly  speaking,  is  not  a 
marble  but  a  serpentine.  It  consists  of  a  mixture  of  serpentine, 
talc  and  dolomite.  Chrysotile,  antigorite  and  magnetite  are  asso- 
ciated minerals.  The  serpentine  of  the  Roxbury  area  is  overlaid 

13 


194 


BUILDING    STONES   AND    CLAYS 


by  green  chlorite  schists.  The  serpentine  itself  is  one  of  the  most 
beautiful  of  all  known  rocks  for  decorative  interior  work.  It 
receives  a  high  polish  which  is  permanent  indoors  but  the  stone 
fades  somewhat  on  exposure  to  the  atmosphere.  The  main  color 
is  a  deep  green  traversed  by  a  network  of  white  veins,  and  often 
patches  of  black.  It  is  unquestionably  one  of  the  most  desirable 
of  all  vercl  antique  marbles.  (See  Figs.  182  and  183.) 

For  a  fuller  description  of  this  serpentine  belt  see  Vermont  in 
Chapter  VII. 


Fig.  181. — Polished  block  of  rhodonite,  Waits  River,  Vermont. 
Photo,  by  C.  H.  Richardson. 

A  larger  amount  of  space  than  would  normally  be  allowed  has 
been  accorded  to  the  marbles  of  Vermont  because  of  the  rank 
the  State  enjoys  as  a  marble  producer. 

Virginia. — The  limestones  and  marbles  of  this  state  occupy 
a  considerable  area  to  the  west  of  the  Blue  Ridge  Mountains. 
They  are  of  Cambro-Ordovician  age.  G.  P.  Merrill  recog- 
nizes the  following  varieties:  (1)  Ne\v  Market  and  Wood- 
stock marble,  which  is  somewhat  coarse  textured  and  sun- 


LIMESTONES,  DOLOMITES  AND  MARBLES      195 

colored.  (2)  New  Market  also  produces  a  coarse  grained, 
mottled  and  bluish  marble.  (3)  Buchanan  marble,  which  is 
fine  grained  and  gray.  (4)  Lexington  marble,  which  is  fine 
grained  and  pure  white.  (5)  Giles  County  marble,  which  is 
fine  grained  and  red.  (6)  Blacksburg  marble,  which  is  fine 
grained  and  black.  (7)  Craigsville  limestone,  which  is  pink, 


Fig.    182. — Unpolished    block    of    Verd    antique    marble,    Roxbury, 
Vermont.     Dimensions  6  by  10  feet.     Photo,  by  C.  H.  Richardson. 


spotted,  and  receives  a  good  polish.  (8)  Tye  River  marble, 
which  is  pure  \vhite  in  color  and  suited  for  statuary  uses. 
(9)  Goose  Creek  marbles,  which  are  fine  grained,  white,  pink 
and  verd  antique.  (10)  Luray  marbles,  which  are  obtained 
from  the  stalagmites  and  stalactites  of  the  Luray  Caverns. 
Some  of  these  onyx  marbles  are  susceptible  of  a  fine  polish. 


196  BUILDING    STONES   AND    CLAYS 

FOREIGN    LIMESTONES    AND    MARBLES 

Africa. — According-  to  G.  P.  Merrill  the  collection  of  marbles 
in  the  National  Museum  from  Africa  contains  a  large  number 
of  handsome  marbles  of  smooth  surface  and  high  polish  desig- 
nated in  the  marts  of  trade  under  the  following  names :  jaune, 
antique  dore,  pavonazzo  rosso,  jaune  chiaro  ondate,  jaune  rose, 
rose  clair,  breche  sanguin,  and  jaspe  rouge. 


Fig.  183. — Old  quarry  in  verd  antique  marble,  Roxbury,  Vermont, 
showing  bench  marks  produced  in  quarrying  the  stone.  Photo,  by 
C.  H.  Richardson. 

Austria. — According  to  J.  A.  Howe  crystalline  limestones 
and  marbles  of  great  beauty  and  value  for  both  structural  and 
ornamental  work  occur  in  Galicia,  Hungary,  Silesia  and  Tyrol. 

Belgium. — The  Belgian  marbles  are  white,  gray,  blue,  black 
and  veined.  The  Belgian  black  marble  is  extremely  fine 


LIMESTONES,  DOLOMITES  AND  MARBLES      197 

grained  like  the  Irish  black  and  receives  a  fine  polish.  Five 
black  marbles  whose  polished  surfaces  closely  resemble  each 
other  and  which  are  substituted  somewhat  for  each  other  for 
decorative  interior  work  are  the  Irish  black,  the  Glens  Falls 
black,  the  Belgian  black,  the  Italian  black  and  the  Isle  La  Motte 
black.  (See  Fig.  184.) 

Bermuda. — According  to  W.  N.  Rice  most  of  the  homes  of 
Bermuda  are  built  of  a  soft  friable  shell  and  coralline  lime- 
stone that  is  a  pure  white.  The  stone  is  whitewashed  to  pre- 
serve it,  even  in  the  mild  climate  of  Bermuda.  It  would  not 
withstand  the  action  of  frost  in  the  northern  portions  of  the 
United  States.  The  Bermuda  limestone  is  in  part  eolian — a 
calc-sand  dune  deposit. 


Fig.  184.— Polished  slab  of  Belgian  black  marble.     Photo,  by  C.  H. 
Richardson. 


British  Columbia. — The  marbles  of  British  Columbia  are 
well  suited  for  structural  and  ornamental  work.  They  are 
white,  gray,  pink  mottled  and  variegated.  They  are  especially 
abundant  on  Taxada  and  Vancouver  Islands. 

England. — According  to  J.  A.  Howe  the  calcareous  forma- 
tions of  England  occur  in  the  Devonian,  Lower  Carboniferous, 
Jurassic  and  Chalk  formations.  The  largest  and  best  quarries 
in  the  Devonian  rocks  are  found  in  South  Devon.  The  pre- 
vailing colors  are  white,  blue  gray,  dark  gray  and  pinkish 
gray.  They  are  well  suited  for  constructional  work  but  not 


198  BUILDING    STONES   AND    CLAYS 

for  piers  and  breakwaters.  The  Carboniferous  limestones 
occur  in  Derbyshire.  The  stone  is  fine  grained,  even  textured, 
of  cream  color  and  weathers  well.  It  is  used  for  monumental 
work,  landings,  steps,  curbs  and  paving  blocks. 

The  landscape  marble  or  forest  marble  that  has  furnished 
so  many  fine  museum  samples  from  the  southwestern  part  of 
England,  is  an  irregular,  argillaceous  and  calcareous  deposit 
that  bears  peculiar  dendritic  markings,  from  which  it  receives 
its  name.  The  stone  is  of  fine  grain,  even  texture,  drab  and 
bluish  colors  and  used  for  walling,  flooring,  pitching  and  farm 
buildings.  The  quarries  are  located  in  Gloucestershire,  Ox- 
fordshire and  Wilts.  (See  Fig.  185.) 


Fig.    185. — Sawn    slab    of    landscape    marble,    England.      Photo,    by 
C.    H.    Richardson. 


Fluoritc.— This  mineral  occurs  in  masses  of  sufficient 
dimensions  in  Derbyshire,  England,  to  be  of  considerable 
economic  importance  as  a  decorative  stone.  It  is  a  marble 
only  in  a  commercial  sense.  (See  Fig.  18(5.) 

France. — The  Griotto,  or  French  Red  marble,  of  the  French 
Pyrenees,  is  one  of  the  handsomest  of  all  known  marbles.  It 
is  of  fine  grain,  even  texture,  and  brilliant  red  color.  It  re- 
ceives a  good  polish.  Small  polished  samples  often  found  in 
drug  stores  are  homogeneous,  but  the  material  used  in  the 
decorations  of  the  Capitol  building  at  Albany,  N.  Y.,  is  full 
of  flaws. 


LIMESTONES,  DOLOMITES  AND  MARBLES      199 

The  Languedoc  marble,  or  French  Red,  is  another  brilliant 
scarlet  colored  marble  that  has  been  quarried  at  Montagne 
Noire  since  the  sixteenth  century.  (See  Fig.  187.) 

The  Caen  stone  is  a  soft,  fine  grained  stone,  light  in  color, 
and  particularly  well  suited  for  carved  work.  It  received  its 
name  from  Caen,  in  Normandy,  where  the  most  important 
quarries  are  located.  These  quarries  are  supposed  to  have 
been  opened  soon  after  the  Norman  conquest.  The  famous 
Cathedral  of  Canterbury  and  Westminster  Abbey  are  from 
this  stone. 


Fig.  186. — Polished  slab  of  fluorite,  Derbyshire,  England.  Photo, 
by  C.  H.  Richardson. 

The  Brocatelle  marble,  \vhich  is  used  so  widely  for  mantels 
and  decorative  interior  work,  is  very  fine  and  compact  in  tex- 
ture, and  of  light  yellow  color,  traversed  by  irregular  veins 
and  blotches  of  dull  red  color.  Its  home  is  in  Jura,  in  eastern 
France. 

Germany. — Nassau,  Germany,  produces  according  to  G.  P. 
Merrill  two  beautiful  marbles.  The  Formosa,  which  is  dark 
gray,  and  white,  mottled  and  blotched  with  red.  The  Bougard, 


200  BUILDING    STONES    AND    CLAYS 

which  is  lighter  in  color  and  whose  tints  are  more  obscure. 
The  Solenhofen  lithographic  limestone  is  of  drab  color. 

Ireland. — The  Carboniferous  limestones  and  marbles  cover 
nearly  all  of  the  center  of  the  island.  The  Brachernagh  marble 
is  a  pale  blue ;  the  Foynes  marble,  gray  and  blue  ;  the  Gillogue 
marble,  blue-black ;  the  Limerick  marble,  bluish  black ;  the 
Lexlip  marble,  black;  the  Skerries  marble,  gray.  It  is  the 
Lexlip  marble  that  receives  the  trade  name  "Irish  black,"  and 
to  which  allusion  has  already  been  made. 

Italy. — The  quarries  of  the  Apennines  in  northern  Italy, 
near  Carrara,  Massa  and  Serravezza,  furnish  marbles  in  beauty 
and  variety  equal  to  any  marbles  of  the  world.  Many  of  these 
marbles  are  largely  imported  for  statuary  purposes  and  deco- 
rative interior  work.  The  decorative  marble  in  the  ne\v  build- 


Fig.  187. — Polished  slab  of  French  red  marble,  Montagne  Noire, 
France.  Photo,  by  C.  H.  Richardson. 

ing  of  the  Syracuse  Trust  Company  came  from  near  the  border 
line  between  Italy  and  France.  It  is  called  the  Travernelle 
Fleuri.  (See  Fig.  188.) 

G.  P.  Merrill,  in  his  "Geology  of  Building  Stones,"  cites  the 
following  varieties:  (1)  White  statuary  marble.  A  fine 
grained  saccharoidal,  pure  white  marble,  without  specks  or 
flaws.  (2)  Ordinary  white  marble.  This  is  a  white  variety 
that  is  sometimes  faintly  bluish  and  veined.  It  is  largely  im- 
ported for  monumental  work.  (3)  The  Bardiglio  is  a  white 
marble  often  blotched  with  darker  hues,  and  traversed  with  a 
network  of  faintly  bluish  lines.  (4)  The  Levante  marble  is  a 
breccia  which  is  composed  of  irregular  \vhitish  and  red  frag- 
ments embedded  in  a  reddish  paste.  (5)  The  Sienna  marbles 


LIMESTONES,  DOLOMITES  AND  MARBLES     201 


Fig.  188. — Polished  slab  of  travernelle  fleuri  marble  from  near  the 
border  between  Italy  and  France.     Photo,  by  C.  H.  Richardson. 


•i 


Fig.   189. — Polished  slab  of  sienna  marble,   Italy.     Photo,  by  C.  H. 
Richardson. 


BUILDING    STONES    AND    CLAYS 


are  varying  shades  of  yellow,  and  often  blotched  with  slightly 
purplish  and  violet  shades.  They  are  fine  grained,  compact 
and  receive  a  polish  equal  to  the  Colorado  siennas.  (6)  The 
Brocatelle  marble  is  of  a  uniform  yellow  color  and  quarried  at 
Monte  Arenti,  in  Montagnola.  It  is  considered  by  many  the 


Fig.    190. — Polished    slab    of    brocatelle    marble,    Italy.      Photo,    by 
C.   1-1.  Richardson. 


r 


Fig.    191.— Polished    slab    of   black   and   gold   marble,    Italy.      Photo, 
by  C.  H.  Richardson. 

most  beautiful  of  all  siennas.  (7)  Portor  or  black  and  gold 
marble  is  found  on  the  Isle  of  Palmaria.  It  is  a  black  siliceous 
limestone  traversed  by  yellowish,  reddish  and  brown  veins  of 
the  carbonate  of  iron.  The  stone  receives  a  high  polish  and  is 


LIMESTONES,  DOLOMITES  AND  MARBLES     203 


Fig.  192.— Polished  slab  of  breccia  marble,  Italy.     Photo,  by  C.   H. 
Richardson. 


Fig.  193. — Polished  slab  of  skyros  marble,  Greece.     Photo,  by  C.  H. 
Richardson. 


204  BUILDING    STONES   AND    CLAYS 

prized  for  decorative  interior  work.  (8)  Black  marble.  This 
stone  is  brought  from  the  Colonnata  quarries  and  closely  re- 
sembles the  Irish  black  marble.  (9)  Breccia  marble.  This 
consists  of  small  bluish  white  fragments  cemented  together 
by  a  chalk-red  cement.  A  second  variety  has  both  white  and 
red  fragments  similarly  cemented.  (10)  Ruin  marble.  This 
is  a  very  compact  yellowish  or  drab  limestone,  the  beds  of 
which  have  been  fractured  in  every  conceivable  direction  and 


Fig.  194. — Polished  slabs  of  onyx  marble,  Mexico.     Photo,  by  C.  H. 
Richardson. 


Fig.  195. — Polished  block  of  stalagmite  marble,  Nova  Scotia.    Photo, 
by  C.  H.  Richardson. 

cemented  together  again.  The  rock  is  strictly  speaking  a 
breccia.  When  cut  and  polished  the  slabs  have  somewhat  the 
appearance  of  mosaics,  representing  the  ruins  of  ancient 
castles  or  other  structures.  Hence  the  name  "ruin  marble." 
(See  Figs.  189,  190,  191  and  192.) 


LIMESTONES,  DOLOMITES  AND  MARBLES     205 


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Greece. — According  to  R.  Swan  the  Island  of  Paros  in  the 
Grecian  Archipelago  produces  two  varieties  of  high  grade 
marble.  The  one  is  a  pure  white  statuary  marble  of  fine  grain 
and  even  texture.  The  other  is  a  decorative  marble  with 
wrhite  body  traversed  by  a  net\vork  of  black  veins.  The  beds 
vary  from  5  to  15  feet  in  thickness  and  dip  at  high  angles.  The 
stone  near  the  axis  of  elevation  is  of  inferior  grade.  (See 
Fig.  193.) 


IIS 


Fig.  201. — Drawings  showing  difference  of  dressed  stone.  A.  Rock 
faced.  B.  Rock  faced  with  tooled  margin.  C.  Broached  stone  with 
tooled  margin.  D.  Rough  pointed  with  tooled  margin.  Drawings  by 
C.  H.  Richardson. 

Mexico. — The  origin  and  characteristics  of  the  onyx  marbles 
have  already  been  described  on  pages  137,  154  and  155.  (See 
Fig.  194.) 

Nova  Scotia. — The  stalagmite  marbles  of  Nova  Scotia  re- 
ceive a  good  polish  and  are  well  adapted  for  decorative  interior 
work.  (See  Fig.  195.) 

Ontario. — Bancroft  marble  represents  a  remarkably  hand- 
some stone  that  has  suffered  brecciation  and  subsequent 
cementation.  Some  portions  of  the  quarries  do  not  show 


LIMESTONES,  DOLOMITES  AND  MARBLES     211 


brecciation,  while  in  others  the  fragments  are  angular. 
Polished  samples  shade  from  white  to  pink  with  a  fine  mottled 
appearance  in  the  brecciated  portions.  It  is  of  even  texture 
and  works  well. 

Hungerford  marble  is  white,  bluish,  greenish  and  sometimes 
pink.  It  takes  a  good  polish. 

Madoc  marble  shades  in  color  from  white,  through  gray  to 
black. 

Renfrew  marble  is  white  and  used  for  structural  purposes. 


O  D 

Fig.  202. — Drawings,  showing  types  of  dressed  stone.  A.  Fine 
pointed  stone  with  margin.  B.  Tooled  stone.  C.  Drove  work.  D. 
Crandalled  stone  with  margin.  Drawings  by  C.  H.  Richardson. 

Quebec. — The  Province  of  Quebec  produces  many  marbles 
that  shade  in  color  from  white  to  red  and  possess  a  fine 
grained,  even  texture.  They  are  used  for  monumental,  struc- 
tural and  decorative  purposes. 

INDUSTRIAL  FACTS  ABOUT  LIMESTONES  AND 
MARBLES 

Quarrying. — In  quarrying  marble  the  object  is  to  obtain 
large  blocks  of  stone  with  the  least  disturbance  possible.  Where 


212  BUILDING    STONES   AND    CLAYS 

the  sheets  are  too  thick  to  split  with  wedges  the  channelling  ma- 
chine is  used  to  cut  vertical  channels  2  inches  wide  and  from  -i 
to  6  feet  deep,  depending  upon  the  thickness  of  the  block 
desired.  This  machine  moves  back  and  forth  over  the  bed  or 
floor  of  the  quarry.  The  gadding  machine  drills  holes  in  the 
face  of  the  block  to  one  half  the  breadth  of  the  block  desired. 
The  stone  may  then  be  lifted  with  wedges.  The  blocks  are 
subsequently  split  into  smaller  dimensions  with  wedgies,  or 


lillllKlllllllllllllllllllllllllllliUlllllllllfllKIUi 


Fig.  203. — Drawings,  showing  different  faces  of  dressed  stone. 
A.  Patent  hammered  with  margin.  B.  Bush  hammered  with  margin. 
C.  Vermiculated  work  with  chiseled  margin.  D.  Fish  scale  work  with 
chiseled  margin.  Drawings  by  C.  H.  Richardson. 

cut  into  slabs  of  varying  thickness  with  a  gang  of  saws. 
Emery  and  chilled  iron  are  used  to  aid  in  the  cutting.  If 
possible,  explosives  should  be  avoided,  as  the  sudden  jar 
develops  incipient  fracture  planes  that  aid  in  the  disintegra- 
tion of  the  stone.  (See  Figs.  196  and  197.) 

Manufacture.— (See  Figs.  ,198,  199  and  200.) 

Dressing. — There  are  many  different  kinds  of  finish  used  for 
building  stones  before  they  are  placed  in  their  position  in  the 


LIMESTONES,  DOLOMITES  AND  MARBLES     213 


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wall  of  the  structure.  (1)  In  cobble  houses  either  glacial 
erratics  (in  the  northern  portions  of  the  United  States),  or  an- 
gular fragments  of  rock  from  quarry  products,  are  laid  in  the 
usual  bond.  These  produce  unique  structures  that  are  pleasing 
in  their  effect. 

(2)   Rock   Face. — Ashlar  blocks   are   laid  practically  as   they 
come  from  the  quarry,  having  been  trimmed  to  a  uniform  size. 


Fig.  208. — Post  Office,  Montpelier,  Vermont,  built  of  Proctor,  Ver- 
mont, marble.  Photo,  by  C.  H.  Richardson. 

Sometimes  the  stone  is  decorated  with  a  margin  of  drove  work. 
(See  Fig.  201.) 

(3)  Uniform  Pointed. — These  blocks  are  trimmed  to  correct 
dimensions  and  the  outer  face  is  then  dressed  with  a  pointing 
instrument.  The  stone  is  decorated  with  a  margin  of  drove 
work.  (See  Fig.  202.) 


218  BUILDING    STONES   AND    CLAYS 

(4)  Diagonal  Pointed. — This  stone  differs  only  in  facial  ap- 
pearance from  the  former,  in  that  the  pointing  runs  in  diagonal 
lines  at  an  angle  of  45°  across  the  stone. 

(5)  Square  Drove. — The  appearance  of  the  face  here  is  pro- 
duced by  a  wide  chisel  with  smooth  edge.     The  lines  through  the 
center  of  the  stone  run  parallel  with  the  base  of  the  block.     The 
margin  is  decorated  with  drove  work. 

(6)  Toothed    Chisel. — The    toothed    chisel    produces    in    the 
center  of  the  face  a  surface  that  somewhat  resembles  tapestry. 
The  margin  is  decorated  as  in  the  previous  cases. 


r* 


Fig.    209. — Capitol    cut    from    Vermont    white    marble.      Photo,    by 
C.    H.    Richardson. 

(7)  Hammered  Pace. — Pean  hammers,   patent  hammers  and 
bush   hammers  produce  different  kinds  of   faces  that  are   fairly 
smooth  and   somewhat  resemble  the  pointed   face  finish.      They 
are  usually  decorated  with  a  margin  of  drove  work.     (See  Fig. 
203.) 

(8)  Grooved  Face. — The   face  of  the  stone  here  produces  a 
grooved  effect.     The  shallow  grooves  run  across  the  entire  face 
parallel  with  the  bed. 


LIMESTONES,  DOLOMITES  AND  MARBLES     219 

(9)  Sawed  Face. — In  this  case  the  blocks  of  stone  are  set  as 
they  are  sawed  out  at  the  mill.     Fine  regular  lines  traverse  the 
face. 

(10)  Smooth  Face. — The  sawed  stone  is   faced  with  a  per- 
fectly smooth  unpolished  surface.     It  may  or  may  not  have  a 
margin  of  drove  work. 

(11)  Polished  Face. — The  sawed  or  chiseled  face  is  rendered 
perfectly  uniform  and  smooth  by  setting  the  entire  block  in  a 
bed  of  plaster  of   Paris  and  using  in  the  order  given,   chilled 
iron,   coarse  emery,   fine   emery,   diatomaceous   earth  and  putty 
powder  or  oxalic  acid.     When  oxalic  acid  is  used  in  the  process 


Fig.  210. — Entrance  to  Green  Mountain  Cemetery,  Montpelier,  Ver- 
mont, built  of  marble  from  West  Rutland,  Vermont.  Photo,  by  C.  H. 
Richardson. 


of  polishing  the  expense  and  time  element  are  less  but  the  polish 
is  short  lived.  Many  decorative  marbles  and  granites  in  our 
cemeteries  that  now  appear  dull  owe  this  condition  largely  to 
the  use  of  oxalic  acid  in  the  process  of  buffing.  Putty  powder 
which  consists  largely  of  the  oxide  of  tin  produces  a  more  ex- 
pensive, more  lasting  and  far  more  satisfactory  polish. 

Hammered  Finish. — The  cost  of  finishing  stone  is  determined 
partly  by  the  shape  and  largely  by  the  smoothness  of  the  surface 
desired.  The  stone  is  finished  by  beating  it  with  hammers  con- 


220 


BUILDING    STONES   AND    CLAYS 


Fig.     211. — Stephen     A.     Douglas 
Photo,   by  J.   F.   Glassony. 


Memorial,     Brandon,     Vermont. 


LIMESTONES,  DOLOMITES  AND  MARBLES     221 

taining  blades  set  at  various  widths.  The  number  of  blades  to 
the  inch  determines  the  fineness  of  the  surface  that  can  be 
secured. 

For  step  work,  approaches  and  the  upper  stories  of  high  build- 
ings, four  cuts  to  the  inch  give  a  satisfactory  finish.  Four-cut 
work  is  specified  by  the  United  States  Government  for  postoffice 
base  courses.  Many  commercial  buildings  are  made  in  this 
finish. 

Six-cut  work  is  the  standard  for  bank  fronts,  private  resi- 
dences, state  capitols,  city  halls,  railroad  terminals,  art  museums, 
fine  bridges,  and  in  general  the  better  class  of  public  and  private 
buildings. 

Eight-cut  work  is  often  specified  on  large  public  memorials, 
elaborate  bank  and  building  entrances,  garden  work,  fountains, 
mausoleum  roof  stones  and  elevated  statuary  groups. 

Ten-cut  finish  is  generally  used  on  monuments,  mausoleums, 
statuary,  and  other  work  which  demands  a  special  smoothness 
of  surface.  Good  stone  with  ten-cut  bushing  shows  a  surface 
smooth  as  velvet  and  free  from  imperfections. 

Uses. — The  limestones  are  used  in  the  manufacture  of  white 
lime  or  tinted  limes.  A  larger  percentage  of  limestone  proper 
goes  into  this  field  than  all  -  other  uses  combined.  This  lime 
product  finds  use  not  only  in  structural  work  but  in  the  beet 
sugar  industry.  Limestones  are  used  for  building  purposes  when 
they  are  of  fairly  uniform  color  and  texture.  They  are  used 
sometimes  for  paving  blocks  but  are  not  resistant  to  abrasion, 
and  for  curbings  and  gutters.  They  find  large  use  as  a  flux  in 
the  treatment  of  iron  ores  and  in  the  manufacture  of  the  numer- 
ous grades  of  Portland  cement.  They  are  used  also  as  a  fertilizer 
and  in  the  manufacture  of  glass. 

The  marbles  find  their  largest  uses  in  structural  and  monu- 
mental work.  The  decorative  marbles  are  used  for  pillars,  colon- 
nades, wainscoting,  panels,  baseboards,  flooring,  tiling,  fire- 
jambs,  lintels,  counters,  shelves,  clocks  and  table  tops.  The 
beautiful  onyx  marbles  find  use  not  only  for  decorative  in- 
terior work  but  also  in  soda  fountains,  shelves,  table  tops  and 
clocks.  (See  Figs.  204,  205,  206,  207,  208,  209,  210  and  211.) 

Compression  Tests. — The  average  strength  of  marbles  is  not 
as  great  as  that  of  granite.  Good  structural  work  should  resist 
from  12,000  to  18,000  pounds  to  the  square  inch.  Some  friable 
marbles  fall  under  these  figures  and  many  good  marbles  exceed 
them.  In  nearly  all  cases  they  are  far  above  the  strength  re- 
quired, even  with  the  builders'  margin  of  safety  added  to  the 
superincumbent  weight. 


222  BUILDING    STONES   AND    CLAYS 

The  following  shows  the  compressive  strength  of  some  of  the 
important  limestones,  marbles  and  dolomites : 

Lbs.  Per  Sq.  In. 

1.  Caen,  France    3,550 

2.  Bedford,  Indiana   10,125 

3.  Italian  marble,  Rutland,  Vt 11,892 

4.  Italian  marble,  Italy 12,156 

5.  Tuckahoe,  N.  Y 13,076 

6.  Tate,  Georgia   13,680 

7.  Rutland,  Vermont    13,864 

8.  Washington,   Vermont    17,675 

9.  Tennessee  marble    18,100 

10.  Cockeysville,    Maryland .20,400 

11.  Lee,   Massachusetts    22,860 

12.  Colville,  Washington .  .24,000 

13.  Champlain  marble,  Vermont   25,000 

Analyses. — A  few  analyses  are  here  given   as  a  matter  of 
reference. 

1.  Oolitic  limestone,  Bedford,  Indiana. 

Calcium  carbonate,  CaCO,    97.26% 

Magnesium  carbonate,  MgCO3   0.37 

Ferric  oxide  and  alumina,  Fe2O3  and  A12O3.  .  .     0.49 
Silica,    SiOo  1-69 


99.81 

2.  Sample  from  Siluria,  Alabama. 

Calcium  carbonate,  CaCO3 98.91 

Magnesium  carbonate,  MgCO3 0.58 

Ferric  oxide  and  alumina,  Fe0O3  and  A1.,O3 .  .  .  0.63 

Silica,    SiCX 0.10 


100.22 

3.  Marble  from  Plymouth,  Vermont.     Analysis  made  by  T.  S. 
Hunt. 

Calcium  carbonate,  CaCO3 53.9 

Magnesium  carbonate,  MgCO3    44.7 

Ferric  oxide  and  alumina,  Fe2O3  and  A12O3.  ...      1.3 

99.9 


LIMESTONES,  DOLOMITES  AND  MARBLES     223 

4.  Marble    from   Brandon,    Vermont.      Analysis   made   by    D. 
Olmstead. 

Calcium  carbonate,  CaCO3 99.55 

Silica,  SiO2    0.29 

Water,  H26,  and  loss 0.20 


100.04 

5.     Marble   from   Isle   La   Motte,   Vermont.     Analysis  by  D. 
Olmstead. 

Calcium  carbonate,  CaCO3 87.94 

Magnesium   carbonate,    MgCO3 4.56 

Ferric  oxide  and  alumina,  Fe2O3  and  A12O3 ....     2.60 

Silica,  SiO2,  and  other  insoluble  matter 4.80 

Water,  H,6,  and  loss 0.10 

Oxide   of   manganese Trace 


100.00 

6.  Siliceous  limestone,  Danville,  Vt.    Analysis  by  D.  Olmstead. 

Calcium  carbonate,  CaCO3   53.50 

Magnesium  carbonate,  MgCO3 2.20 

Ferric  oxide  and  alumina,  Fe2O3  and  A12O3.  ...      1.90 

Silica,  SiO2,  and  insoluble  silicates 38.90 

Water,  H26,  and  loss 3.50 


100.00 
7.  Sample  from  Carrara,  Italy. 

Calcium  carbonate,  CaCO3 : 99.77 

Magnesium  carbonate,  MgCO3 0.90 

Silica,  SiO2 0.16 

Ferric  oxide  and  alumina,  A12O3,  Fe2O3 0.08 


99.91 

8.  Sample  of  white  Norwegian  marble  from  Velfjorden,  Tro- 
\'iken. 

Calcium  carbonate,  CaCO3 99.27 

Iron  carbonate,  FeCO3 0.137 

Manganese  carbonate,  MnCO3  0.0026 

Magnesium  carbonate,  MgCO3 0.68 

Insoluble  matter    0.77 


100.86 


224 


BUILDING    STONES   AND    CLAYS 


9.  Sample  of  marble  from  Lee,  Mass. 

Calcium  carbonate,  CaCO3    54.16 

Magnesium  carbonate,  MgCO3 45.09 

Iron  carbonate,  FeCO3 0-32 

Insoluble   matter    0.46 

100.03 

10.  The    following   composite    analysis    of   498   constructional 
limestones  was  furnished  by  H.  N.  Stokes. 

Silica,  Si02    14.09 

Titanium  dioxide,  TiO2   0.08 

Alumina,  A12O3   1.75 

Iron  oxides,  ~Fe2O3,  FeO   0.77 

Manganous  oxide,   MnO    0.03 

Calcium  oxide,  CaO   40.60 

Magnesia,  MgO 4.49 

Potash,  K,O 0.58 

Soda,  Na2O    0.62 

Lithia,    LioO    Trace 

Water  combined,  H2O   0.30 

Water  uncombined  and  organic  matter 0.88 

Phosphorous  oxide,  P2O5 0.42 

Carbon   dioxide,   CCX    35.58 

Sulphur,   S    ".. 0.07 

Sulphur  trioxide,  SO,    0.07 

Chlorine,  Cl   .                             0.01 


100.34 


LIMESTONES,  DOLOMITES  AND  MARBLES     225 


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226  BUILDING    STONES   AND    CLAYS 

REFERENCES 

Aubury,  L.  E. — Structural  and  Industrial  Materials  of  Cali- 
fornia; 1906. 

Baker,  R.  T. — Building  and  Ornamental  Stones  of  New  South 
Wales,  2nd.  Edition;  Technological  Museum,  1909. 

Beare,  T.  H. — Building  Stones  of  Great  Britain ;  London,  1892. 

Brinsmade,  R.  B. — Marble  Quarrying  of  Gouverneur,  N.  Y. ; 
Eng.  and  Min.  Journal,  Vol.  80,  1905. 

Buckley,  E.  R. — Building  and  Ornamental  Stones  of  Wis- 
consin; 1898. 

Burnham,  S.  M. — History  and  Uses  of  Limestones  and  Mar- 
bles; Boston,  1883. 

Butts,  L. — Variegated  Marble  Southeast  of  Calera,  Shelby 
County,  Ala. ;  Bull.  U.  S.  Geol.  Survey,  No.  470,  1911. 

Byrne,  P. — Marble  Formations  of  the  Cahaba  River,  Alabama ; 
Eng.  and  Min.  Journal,  Vol.  72,  1901,  p.  400. 

Clute,  F.  P. — History  of  the  Marble  Industry  in  Tennessee; 
Fifth  Ann.  Report,  Bureau  of  Labor,  Statistics  and  Mines, 
Nashville,  1896. 

Dale,  T.  N. — The  Commercial  Marbles  of  Western  Vermont; 
Bull.  U.  S.  Geol.  Survey,  521,  1912. 

Dale,  T.  N.— The  Calcite  Marble  and  Dolomite  of  Eastern 
Vermont;  Bull.  U.  S.  Geol.  Survey,  589,  1915. 

Day,  A.  W. — The  M.arble  Quarries  of  Carrara,  Italy ;  Sci.  Am., 
Nov.  26,  1907. 

Eckel,  E.  C.— Building  Stones  and  Clays;  Their  Origin,  Char- 
acters and  Examination ;  John  WTiley  and  Sons,  1912. 

Gordon,  C.  H. — The  Marbles  of  Tennessee;  Tennessee  Geol. 
Survey,  1911. 

Herrmann,  O. — Steinbruch  -  Industrie  und  Steinbruch  -  Geolo- 
gic;  Berlin,  1899. 

Hopkins,  T.  C. — Marbles  and  Other  Limestones ;  Ann.  Report 
Geol.  Survey  of  Arkansas,  Vol.  4,  1893. 

Howe,  J.  A. — The  Geology  of  Building  Stones ;  E.  Arnold, 
London,  1910. 

Hull,  Edward — A  Treatise  on  the  Building  and  Ornamental 
Stones  of  Great  Britain  and  Foreign  Countries;  E.  Ar- 
nold, London,  1910. 

Humphrey,  H.  L.  —  Fire-Resistive  Properties  of  Various 
Building  Materials;  Bull.  U.  S.  Geol.  Survey,  No.  370, 
1909. 


LIMESTONES,  DOLOMITES  AND  MARBLES     227 

Jackson,  A.  W. — Building  Stones  of  California ;  Ann.  Report, 

State  Mineralogist,  1888. 
Julien,    A.    A. — The    Durability    of    Building    Stones;    Tenth 

Census  U.  S.,  Vol.  10,  1884,  pp.  366-367. 
Julien,    A.    A. — The    Decay    of    the    Building    Stones    of    New 

York  City ;  Trans.  New  York  Acad.  Sci.,  Vol.  2,  1882-1883, 

pp.  67-79,  120-138. 

Keith,  A.— Tennessee  Marbles;  Bull.  U.  S.  Geol.  Survey,  No. 
213,  1902. 

Lee,  A. — Marble  and  Marble  Workers;  1887. 

McCalley,  Henry — The  Coosa  Valley  Region ;  Report  on  the 
Valley  Regions  of  Alabama,  Pt.  2,  Alabama  Geol.  Sur- 
vey, 1897. 

McCallie,  S.  W. — A  Preliminary  Report  on  the  Marble  of 
Georgia;  Bull.  Geol.  Survey  of  Georgia,  No.  1,  1894. 

Mathews,  E.  B. — An  Account  of  the  Character  and  Distribu- 
tion of  Maryland  Building  Stones,  Vol.  II,  Maryland 
Geol.  Survey,  1898. 

Mathews,  E.  B.  and  Grasty,  J.  S. — Report  on  the  Limestones 
of  Maryland;  Vol.  VIII,  Part  III,  Maryland  Geol.  Sur- 
vey, 1909. 

Merrill,  G.  P. — Stones  for  Building  and  Decoration ;  3rd  Ed., 
1908. 

Middleton,  G.  A. — Building  Materials;  London,  1905. 

Parks,  W.  A. — The  Building  Stones  of  Canada;  Can.  Mines 
Branch,  Vol.  I:  Rept.  No.  100  (Ontario);  1912.  Vol.  II: 
Rept.  No.  203  (Maratime  Provinces);  1914.  Vol.  Ill: 
Rept.  No.  279  (Quebec);  1914.  Vol.  IV:  Rept.  No.  388 
(Western  Provinces)  ;  1916. 

Perkins,  G.  H. — Report  on  the  Marble,  Slate  and  Granite  In- 
dustries of  Vermont;  1898. 

Perkins,  G.  H.— Report  of  the  Vermont  State  Geologist;  1914. 

Prouty,  W.  F. — Crystalline  Marbles  of  Alabama,  Bull.  G.  S. 
A.,  Vol.  27,  No.  2. 

Prouty,  W.  F. — Marbles  of  Alabama;  Bull.  Geol.  Survey  of 
Ala.,  No.  18,  1916. 

Richardson,  C.  H. — The  Terranes  of  Orange  County,  Ver- 
mont; Ann.  Report  State  Geologist,  1902. 

Ries,  H. — Economic  Geology;  John  Wiley  and  Sons,  New 
York,  1916. 


228  BUILDING    STONES    AND    CLAYS 

Ries,  H. — Building  Stones  and  Clay  Products;  J.  Wiley  and 
Sons,  1912. 

Schmid,  H. — Die  Modernen  Marmore  und  Alabaster;  Leipsig 
and  Vienna,  1897. 

Shedd,  S. — The  Building  and  Ornamental  Stones  of  Wash- 
ington; Ann.  Report  Washington  Geol.  Survey,  Vol.  2, 
1903. 

Watson,  J. — Building  Stones;  Cambridge  Press,  1911. 

Wright,  C.  W. — The  Building  Stones  and  Materials  of  South- 
eastern Alaska;  Bull.  U.  S.  Geol.  Survey,  No.  345,  1908. 


CHAPTER  V 

SANDSTONES 

Definition. — Sandstones  belong  to  the  sedimentary  and  de- 
trital  rocks.  They  represent  the  reconsolidated  products  of 
rock  decomposition.  They  consist,  therefore,  of  grains  of 
sand  held  together  by  some  cementing  material.  Pressure 
alone  may  accomplish  this  as  in  the  flexible  sandstone  of 
North  Carolina,  or  it  may  be  effected  by  the  addition  of  some 
cementing  material. 

Chemical  Composition. — Sandstones  differ  in  composition 
as  widely  as  the  sands  of  the  sea  shore  or  the  river  banks. 
In  one  respect  there  is  a  wide  difference  and  that  is  the 
presence  of  the  cementing  materials.  Essentially  they  repre- 
sent grains  of  quartz,  SiO2,  and  some  cement.  There  are 
many  other  minerals  like  the  amphiboles,  pyroxenes,  magne- 
tite, chromite,  cassiterite  and  monazite  that  may  resist  de- 
composition and  remain  near  the  place  where  they  were  de- 
rived as  sand. 

Impurities. — The  impurities  are  the  minerals  normal  to  the 
sand  beds  that  suffered  cementation  and  their  metamorphic 
derivatives.  Siderite,  pyrite,  garnet,  muscovite  and  biotite 
may  appear.  These  can  all  be  detected  by  methods  already 
cited. 

Texture. — The  texture  of  sandstones  varies  from  the  fine- 
ness of  dust  particles,  sandy  material  that  may  be  held  in 
suspension  for  a  considerable  period  of  time  and  deposited, 
to  individual  pieces  several  inches  in  diameter.  When  these 
larger  rock  fragments  are  water  worn  and  well  rounded  the 
stone  passes  over  into  a  conglomerate.  When  the  fragments 
are  distinctly  angular  the  stone  becomes  a  breccia.  The  term 
conglomerate  is  sometimes  used  to  cover  the  breccias.  In 
the  case  of  the  conglomerates  the  fracture  is  often  around  the 
coarser  fragments  and  in  the  quartzites  across  them.  (See 
Fig.  212,  .and  also  Fig.  10.) 

Color. — The  color  of  sandstones  is  widely  varied.  It  may 
arise  from  the  color  of  the  individual  sand  grains  themselves 
or  from  the  character  of  the  cements  introduced.  The  color 
is  more  dependent  upon  the  nature  or  composition  of  the 
cementing  material  than  it  is  upon  the  color  of  the  sand  grains. 

229 


230 


BUILDING    STONES   AND    CLAYS 


Fig.  212. — Fine  grained  red  sandstone,  Portage,  Wisconsin, 
by  C.   H.  Richardson. 


Photo. 


Fig.    213. — Brownstone,    Hummelstown,    Pennsylvania.      Photo,    by 
C.  H.  Richardson. 


SANDSTONES  231 

If  the  cement  is  the  anhydrous  oxide  of  iron  the  stone  will 
be  red.  If  it  is  the  hydrated  oxide  of  iron  the  stone  will  be 
yellow  or  yellowish  brown.  If  it  is  clayey  matter  the  stone 
may  be  gray  or  blue.  Blue  coloration  may  also  be  caused 
by  microlites  of  pyrite,  and  the  gray  by  microlites  of  siderite. 
If  the  cement  is  pure  silica  and  the  original  sand  grains  con- 
sisted of  white  quartz  the  metamorphic  product,  quartzite, 
will  be  white.  The  prevailing  colors  are  white,  light  gray, 
gray,  drab,  blue,  buff,  yellow,  yellowish  brown,  reddish  brown 
and  red.  (See  Figs.  213,  214  and  215.) 

Varieties. — The  different  varieties  are  based  upon  several 
factors  as  mineral  composition,  structure,  and  the  character  of 
the  cementing  material.  The  cementing  material  may  be  calcium 


Fig.  214. — Reddish  brown  sandstone,  Potsdam,  New  York.     Photo: 
by  C.  H.  Richardson. 

carbonate.  The  product  is  then  called  a  calcareous  sandstone. 
It  passes  by  insensible  gradations  into  a  siliceous  limestone.  A 
kaolinitic  sandstone  is  one  whose  cement  is  kaolinite.  A  glau- 
conitic  sandstone  is  one  containing  green  sand  marl.  An  argilla- 
ceous sandstone  is  one  bearing  a  considerable  amount  of  clayey 
matter.  It  may  pass  insensibly  into  a  shale.  A  ferruginous  sand- 
stone is  one  bearing  some  compound  of  iron.  Such  sandstones 
may  reveal  the  presence  of  the  iron  by  their  color.  A  bituminous 
sandstone  is  one  bearing  bitumen.  It  emits  an  organic  odor  when 
strongly  heated.  A  feldspathic  sandstone,  as  the  name  implies, 
contains  fragments  of  feldspars  in  addition  to  the  grains  of  silica 
or  quartz.  Its  parent  source  was  the  decomposition  of  some 
granite  or  gneiss.  In  its  metamorphism  it  passes  into  a  gneiss. 


232 


BUILDING    STONES   AND    CLAYS 


A  quartzite  is  a  metamorphic  sandstone  whose  cement  is  silica. 
A  greywacke  is  a  sandstone  consisting  essentially  of  quartz, 
feldspar  and  fragments  of  slate,  bound  together  by  argillaceous, 
calcareous,  or  even  feldspathic  material.  According  to  C.  P. 
Berkey  secondary  chlorite  constitutes  the  main  bonding  mate- 
rial in  the  Hudson  River  bluestone.  Flagstone  is  a  name 
derived  from  the  ease  with  which  a  sandstone  splits  into  slabs 
suitable  for  flagging  or  sidewalks.  Freestone  is  the  name 
applied  to  the  varieties  of  sandstone  that  split  freely  in  all  direc- 
tions. (See  Fig.  216.) 


Fig.  215. — Blocks  of  gray  sandstone,  Cobleskill,  New  York,  de- 
signed for  constructional  work  in  New  York  City.  Photo,  by  C.  H. 
Richardson. 

Cements. — The  cements  in  sandstones  are  as  varied  as  the 
sandstones  themselves.  Pressure  alone  may  cause  the  sand 
grains  to  interlock  and  produce  a  friable  and  flexible  variety 
known  as  itacolumyte.  Percolating  waters  charged  with 
calcium  carbonate  provide  the  carbonate  for  binding  the  sand 
grains  together.  This  cement  may  be  identified  by  its  effer- 
vescence with  cold  dilute  HC1.  The  amount  of  this  cementing 
material  may  be  quite  subordinate,  or  the  percentage  of 
cement  may  equal  that  of  the  sand. 

A.  von  Morlot  cites  calcite  crystals  from  Fontainebleu  that 
contain  50  per  cent  of  calcium  carbonate,  others  that  carry 


SANDSTONES 


233 


58  per  cent  of  sand  and  still  others  that  bear  95  per  cent,  of 
sand.  S.  L.  Penfield  and  W.  E.  Ford  have  shown  the  com- 
position of  similar  calcites  from  the  Bad  Lands  of  South 
Dakota  to  be  60  per  cent  of  sand  and  40  per  cent  of  calcium 
carbonate. 

L.  Cayeux  describes  the  gaize  of  the  French  geologists  as 


wit  r 


If   . 


r 


Fig.  216. — Jeudevine  memorial  library,  Hardwick,  Vermont,  built 
of  Triassic  sandstone  from  the  Connecticut  Valley.  Photo,  by  C. 
H.  Richardson. 

a  siliceous  sandstone  containing  quartz  and  glauconite  which 
are  cemented  together  by  opaline  silica,  clay,  chalcedony  and 
the  carbonate  of  lime.  The  percentage  of  calcium  carbonate  is 
usually  small,  but  in  some  instances  it  has  risen  sufficiently 
high  to  cause  the  rock  to  be  called  a  calcareous  sandstone.  The 
silica  ranges  from  76  per  cent  to  92  per  cent  and  is  soluble 


234  BUILDING    STONES   AND    CLAYS 

in  caustic  alkalies  up  to  75.3  per  cent.  Ordinary  quartz  is 
sparingly  soluble  in  a  weak  alkali,  but  opaline  silica  passes 
readily  into  solution. 

Silica  itself  may  serve  as  the  cementing  substance.  It  may 
appear  either  as  the  amorphous  silica  or  in  crystalline  form. 
In  the  former  case  the  silica  fills  the  interstices  between  the 
sand  grains,  while  in  the  latter  case  the  sand  grains  themselves 
become  the  nuclei  for  distinct  quartz  crystals.  C.  R.  Van 
Hise  in  his  classic  "Treatise  on  Metamorphism"  states  that 
when  the  sand  grains  are  of  equal  dimensions  the  maximum 
pore  space  reaches  24  per  cent,  but  the  actual  space  on  account 
of  the  irregularity  or  inequality  of  the  grains  is  usually  much 
greater.  With  silica  as  a  cement  there  is  every  gradation 
possible  between  a  friable  rock  and  a  compact  solid  rock  which 
in  its  metamorphism  passes  into  a  hard,  vitreous  quartzite 
with  the  longest  life  of  any  known  building  stone. 

The  anhydrous  and  hydrous  oxides  of  iron  serve  often  as 
the  cementing  material.  These  cements  impart  their  charac- 
teristic colors  to  the  sandstone  in  which  they  appear.  Hema- 
tite tends  to  impart  a  red  color.  The  sandstones  of  the  south- 
ern shore  of  Lake  Superior  bear  this  cement.  The  Triassic 
sandstones. of  New  England  bear  limonite  and  turgite.  The  Ter- 
tiary sandstones  of  the  Appalachians  carry  turgite.  Some  of 
these  sandstones  are  fairly  permanent. 

The  hydroxide  of  aluminum  as  well  as  clayey  matter  may 
fill  the  interstitial  spaces  between  the  sand  grains  and  form  a 
fairly  satisfactory  stone  for  structural  work.  The  fine  grained 
bluestone  of  Warsaw,  N.  Y.,  carries  clay.  It  is  detected  by 
its  argillaceous  odor  and  aluminous  taste.  According  to  G.  P. 
Merrill  clayey  matter  is  objectionable  as  a  cement  because  it 
readily  absorbs  water  and  renders  the  stone  more  subject  to 
injury  by  frost. 

F.  Clowes  cites  barytic  sandstones  in  which  barium  sulphate 
serves  as  the  cement.  Sometimes  more  than  50  per  cent  of 
BaSO4  is  present.  The  waters  in  this  case  percolating  through 
the  sand  beds  bore  barium  carbonate  and  soluble  sulphates 
which  would  react  upon  each  other,  forming  barium  sulphate 
and  some  soluble  carbonate.  Such  a  sandstone  would  be  most 
durable  on  account  of  the  insolubility  of  the  cementing 
material. 

B.  Doss  has  described  crystals  of  gypsum  from  the  Astrakan 
steppe  which  contain  48.58  per  cent  of  sand  and  also  cites 
gypsiferous  sandstones.  C.  W.  Hayes  has  described  a  sand- 
stone from  Tennessee  in  which  calcium  phosphate  serves  as 


SANDSTONES  236 

the  matrix  of  the  sand  grains.  C.  Claus  cites  a  sandstone 
from  Kursk,  Russia,  that  bears  22.64  per  cent  of  calcium  phos- 
phate. G.  P.  Merrill  cites  the  phosphates  of  iron  as  rare 
cementing  material  in  sandstones.  M.  Mackie  cites  calcium 
fluoride  as  the  cement  in  the  sandstones  from  Elginshire, 
Scotland,  which  in  exceptional  cases  bears  25.88  per  cent 
fluorite.  F.  W.  Clarke  cites  bituminous  substances  serving  as 
cement  and  further  states  that  any  substance  which  waters 
can  deposit  in  a  relatively  insoluble  condition  may  serve  as  a 
cement. 

Origin. — Sandstones  are  sedimentary  or  detrital  in  origin, 
beds  of  sand  deposited  by  waters  when  their  velocity  was 
checked  ultimately  became  consolidated  by  the  influence  of 
any  one,  or  more  than  one,  of  the  cements  already  enumerated. 
Any  rock  forming  mineral  which  can  survive  the  destruction 
of  the  parent  rock  mass  may  appear  amongst  the  sand  de- 
posits and  therefore  be  present  in  the  resulting  sandstones. 

Age. — Sandstones  are  not  confined  to  the  rocks  of  any  par- 
ticular geological  age.  They  appear  in  the  rocks  of  all  ages 
from  the  Archaean  to  the  present  time.  Commercial  sand- 
stones, however,  are  not  younger  than  the  Cretaceous. 

AMERICAN  SANDSTONES 

Alabama. — Sandstones  of  Lower  Carboniferous  age  have 
been  worked  in  this  state  at  Cherokee,  Colbert  County.  They 
are  known  as  the  Hartswellville  stone.  Carboniferous  sand- 
stones are  quarried  at  Cullman,  Jasper  and  Tuscaloosa.  These 
sandstones  are  used  largely  in  river  engineering.  The  Weisner 
quartzite  is  used  for  structural  purposes.  It  is  of  Cambrian 
age. 

Arizona. — Triassic  sandstones  occur  in  Flagstaff,  Yavapai 
County.  They  are  of  fine  grain  and  even  texture.  They  shade 
in-color  from  a  light  pink  through  a  brown  to  red.  The  cement 
is  calcium  carbonate  and  the  oxides  of  iron. 

Arkansas. — According  to  J.  C.  Branner  the  northern  part 
of  the  state  contains  a  cream  colored  calciferous  sandstone 
which  on  account  of  its  color,  massiveness,  and  firmness,  is 
desirable  for  achitectural  purposes.  D.  D.  Owen  cites  brown 
massive  sandstones  in  Van  Buren  County.  Gray  sandstones 
of  Carboniferous  age  are  also  quarried.  Buff  colored  sand- 
stones occur  in  the  Boston  Mountains.  They  have  been  quar- 
ried somewhat  in  the  northwestern  part  of  the  state.  The 
Batesville  sandstone  of  Independence  County  is  cream  colored 


236  BUILDING    STONES   AND    CLAYS 

and  used  largely  in  the  construction  of  the  business  section  of 
Batesville. 

The  peculiar  novaculites  of  Arkansas  which  have  been  so 
widely  used  as  hones  are  worthy  of  special  mention.  L.  S. 
Griswold  considered  them  as  a  siliceous  sediment  or  silt,  and, 
therefore,  a  sandstone  of  extremely  fine  grain.  He  found  no 
organisms  in  the  novaculite  and  no  appreciable  amount  of 
soluble  silica.  All  gradations  exist  between  shale  and  novacu- 
lite. F.  Rutley  considers  the  novaculite  a  replacement  deposit 
or  pseudomorph  after  limestone  or  dolomite.  The  novaculite 
has  also  been  regarded  as  a  chemical  precipitate,  analogous 
to  siliceous  sinter.  Whatever  its'  origin  may  have  been  it  is 
exceedingly  fine  grained  and  nearly  pure  silica. 

California. — The  sandstones  of  Alameda  County  are  used 
for  macadam,  rubble,  concrete,  foundations  and  cemetery 
work.  The  stone  is  massive  and  buff  colored.  Amador  County 
is  the  home  of  the  red  sandstone  used  in  the  California  Bank 
Buildings  at  Sacramento,  and  in  the  Chronicle  Building  at 
San  Francisco.  About  300  feet  to  the  north  of  the  red  quarry 
there  occurs  a  massive  snow-white  sandstone  that  is  free  from 
iron  and  well  adapted  for  constructional  work.  The  waste 
can  be  used  by  the  glass  and  pottery  manufacturers.  Cala- 
veras  County  has  produced  a  medium  grained,  wrhite  sand- 
stone. Colusa  County  produces  a  bluish  gray  and  buff  sand- 
stone that  occurs  in  beds  totalling  from  125  to  225  feet  in  thick- 
ness. Contra  Costa  County  furnishes  a  fine  grained,  light  blue 
sandstone  that  makes  a  firm  building  stone.  Kern  County 
produces  sandstones  that  are  fine  grained,  drab,  blue,  tan,  red 
and  green  in  color.  Los  Angeles  County  furnishes  a  fine 
grained  tawny  colored  sandstone  that  is  represented  in  the 
Courthouse  at  San  Bernadino  and  in  the  Public  Library  at 
Santa  Ana.  Napa  County  quarries  light  gray,  bluish  gray 
and  buff  sandstones  that  are  used  locally.  Santa  Barbara 
County  produces  a  buff  colored,  coarse  grained  arkose  sand- 
stone that  is  used  for  building  purposes.  Santa  Clara  County 
furnished  the  buff  sandstone  for  the  Carnegie  Library  at  Santa 
Cruz.  Ventura  County  possesses  a  coarse  grained,  rich  purp- 
lish brown  sandstone  and  a  fine  grained,  light  reddish  brown 
stone  that  works  easily  and  is  very  durable.  The  stone  is 
known  as  the  Sespe  brownstone  and  is  largely  used  for  con- 
structional work  in  many  cities  in  the  state. 

Colorado. — According  to  G.  H.  Eldridge  the  sandstones  of 
the  state  fall  into  three  distinct  varieties,  (1)  The  Fountain 
sandstone  which  is  fine  grained  and  of  light  color  and  well 


SANDSTONES  237 

adapted  for  a  wide  variety  of  architectural  purposes.  Its  age 
is  Pennsylvanian.  (2)  The  second  is  a  hard,  banded  variety 
that  is  a  favorite  for  flagging  and  foundations  on  account  of 
its  high  compression  strength.  (3)  The  third  is  a  hard  white 
or  creamy  white  quartzite  well  suited  for  curbing,  paving, 
flagging,  underpinnings,  etc.  The  Triassic  salmon  red  stone 
from  Jefferson  County  finds  a  ready  market  in  Chicago.  The 
light  colored  sandstone  found  in  the  Court  House  at  Denver 
came  from  Canon  City. 

Connecticut. — According  to  J.  D.  Dana  the  well  known  belt 
of  Triassic  sandstones  traverses  Connecticut  and  Massachu- 
setts in  a  north  and  south  direction  a  distance  of  110  miles 
with  an  average  width  of  20  miles.  The  first  known  quarry- 
ing of  sandstone  in  America  antedated  1665  and  was  executed 
at  Portland  and  Middletown,  where  the  rocks  hang  shelving 
over  the  river.  The  Portland  beds  lie  in  nearly  a  horizontal 


Fig.    217. — Brown    sandstone,     Middlesex    quarry,     Portland,    Con- 
necticut.    Photo,  by  C.  H.  Richardson. 

position.  The  vertical  walls  now  rise  on  three  sides  for  hun- 
dreds of  feet  above  the  quarry  floor.  Blocks  of  any  dimension 
can  be  obtained.  The  stone  grades  from  fine  to  medium  in 
texture  and  is  of  uniform  reddish  brown  color.  The  stone  in 
some  localities  bears  scales  of  muscovite  set  with  cleavage 
parallel  to  the  bedding  planes  of  the  stone.  Such  blocks  when 
set  on  bed  are  fairly  permanent,  but  if  set  so  that  pressure  is 
parallel  with  the  cleavage  in  the  mica  the  stone  shows  a  ten- 
dency to  scale  upon  exposure  to  the  atmosphere.  The  com- 
pression test  when  made  \vith  the  stone  set  on  edge  is  lower 
than  on  the  bed.  (See  Fig.  217.) 


238  BUILDING    STONES   AND    CLAYS 

Georgia. — This  state  is  known  to  carry  in  the  Chattooga 
Mountains  a  wide  variety  of  sandstones  of  even  texture  and 
of  white,  gray,  buff,  brown  and  red  colors. 

Idaho. — G.  P.  Merrill  cites  the  presence  in  the  National 
Museum  in  Washington  of  a  coarse  and  light  colored  sand- 
stone from  Boise  City. 

Illinois. — Sandstones  occur  in  this  state  in  Carroll,  Greene, 
Henry,  Marion,  Randolph  and  St.  Claire  Counties.  They 
shade  in  color  from  a  light  bluish-gray  color  to  a  dark  brown 
color.  In  both  .color  and  texture  they  resemble  the  Triassic 
sandstone  of  the  Connecticut  valley.  They  are  Carboniferous 
in  age. 

Indiana. — According  to  T.  C.  Hopkins  the  Mansfield  sand- 
stone is  the  most  important  sandstone  in  the  state  both  from 
an  economic  and  a  scientific  standpoint.  It  is  a  massive  coarse 
grained  stone  whose  colors  are  gray,  yellow,  brown,  red  and 
variegated.  The  quartz  grains  in  the  brownstones  of  Indiana 
are  themselves  white  or  colorless.  They  are  encircled  by  a 
film  of  iron  oxides  to  which  the  color  of  the  stone  is  due.  The 
cementing  material  varies  from  2  to  35  per  cent.  Hopkins 
further  states  that  there  are  many  shades  of  the  red  and  brown 
colors,  one  of  the  most  common  being  a  deep  reddish  brown 
with  a  faint  purple  tinge  suggestive  of  manganese,  and  having 
a  faint  steel  luster  in  places.  It  is  a  handsome  stone  and  de- 
sirable for  building  purposes.  Another  common  shade  is  a 
lighter  red  than  the  preceding  variety.  The  lighter  color  is 
due  in  part  to  the  greater  abundance  of  white  granular  quartz 
and  in  part  to  a  thinner  coating  of  the  oxide  of  iron  on  the 
grains  themselves.  It  is  considered  handsomer  than  the  pre- 
ceding variety.  Another  shade  is  a  walnut  brown.  Still  an- 
other variety  is  called  a  "flea-bitten  fawn  skin."  It  consists 
of  a  light  brown  body  with  light  gray  spots  about  the  size  of 
the  tip  of  the  finger.  The  stone  near  Green  Hill  is  a  little 
lighter  red  than  a  cherry.  It  is  a  clearer  red  than  any  other 
sandstone  of  the  state. 

The  yellow,  buff  and  gray  Mansfield  sandstone  is  more 
abundant  than  the  brown  and  red  varieties.  The  difference 
lies  largely  in  the  iron  content  of  the  cement.  The  nearly 
white  sandstone  is  practically  free  from  iron.  The  Mansfield 
sandstones  are  of  great  durability  and  preferable  to  the  Trias- 
sic brownstones  of  the  Appalachian  belt.  They  are  adapted 
to  rock  masonry  of  all  kinds  where  they  are  not  subject  to 
great  transverse  strain,  violent  abrasion,  or  require  a  smoothly 
finished  or  carved  surface. 


SANDSTONES 


239 


Portland  Sandstone. — The  Portland  sandstone  at  Worthy, 
Vermillion  County,  is  one  of  the  best  building  stones  of  the 
state.  The  stone  is  of  even  texture  and  in  color  is  light  buff 
near  the  surface  and  bluish  gray  with  depth.  It  occurs  in 
massive  beds  more  than  50  feet  in  thickness  and  overlain  with 
shale,  coal  and  glacial  drift. 

Riverside  Sandstone. — The  Riverside  sandstone  occurs  at 
Riverside,  Fountain  County.  The  stone  is  extremely  fine 
grained,  receives  a  perfectly  smooth  finish  and  is  well  adapted 
to  delicate  carving  and  ornamentation.  In  color  it  is  a  drab 
or  buff  on  the  exterior,  with  a  light  blue  interior..  It  is  not  as 
durable  a  stone  as  the  Mansfield  brownstone  but  it  is  better 
adapted  to  trimming  or  carved  work.  (See  Fig.  218.) 


Fig.  218. — Fine  grained  gray  sandstone,  Riverside,  Indiana.  Photo, 
by  C.  H.  Richardson. 

Iowa. — Coarse  dark  brown  sandstones  of  Carboniferous  and 
Cretaceous  ages  are  quarried  in  Case  and  Muscatine 
Counties. 

Kansas. — Sandstones  are  quarried  in  the  southwestern  part 
of  the  state  in  Bourbon,  Crawford,  Elk,  Greene,  Labette, 
Montgomery,  Wilson  and  Woodson  Counties.  They  are  fine 
grained,  even  textured  stones  of  bluish-gray  and  brown  colors. 
Their  use  is  largely  local. 

Kentucky. — In  this  state  sandstones  are  quarried  in  Breck- 
enridge,  Grayson,  Johnson,  Simpson  and  Todd  Counties.  They 
are  very  fine  grained  and  of  even  texture.  In  colors  they 
shade  from  a  light  buff  to  a  pink  and  are  used  locally. 

Maine. — Brown  and  red  sandstones  of  Devonian  and  Trias- 
sic  age  occur  in  this  state  in  Washington  County  and  at 
Machiasport.  They  are  not  extensively  quarried. 

Maryland. — A   Triassic    sandstone    occurs    about    30    miles 


240 


BUILDING    STONES   AND    CLAYS 


northwest  of  Washington  in  Montgomery  County.  It  is  of 
fine  grain  and  even  texture.  In  color  it  is  a  light  reddish 
brown  of  pleasing  effect.  It  is  well  adapted  for  all  manner 
of  building  and  ornamental  \vork.  It  is  one  of  the  most 
durable  of  all  the  Triassic  sandstones.  It  can  be  seen  by 
any  visitor  in  Washington  for  the  Smithsonian  Institution  was 


Fig.  219. — Grouse  College  at  Syracuse  University,  Syracuse,  New 
York,  built  of  Triassic  sandstone  from  East  Longmeadow,  Massa- 
chusetts. Photo,  by  I.  U.  Doust. 

constructed  from  this  stone  in  1848-54.  G.  P.  Merrill  states 
that  these  blocks  show  few  defects  from  weathering  alone 
and  that  even  these  might  have  been  avoided  by  a  more 
judicious  selection  of  the  stone.  The  walls  of  the  Chesa- 
peake and  Ohio  Canal  contain  this  stone. 

Massachusetts. — The  Triassic  sandstones  of  the  Connecti- 


SANDSTONES 


211 


cut  Valley  have  been  quarried  from  the  beginning  of  the 
sandstone  industry  in  the  United  States.  The  length  and 
breadth  of  the  belt  has  already  been  described  under  the 
caption  of  Connecticut.  The  best  known  quarries  in  Massa- 
chusetts are  located  at  East  Longmeadow  and  Kibbe,  in 
Hampden  County.  The  stone  is  of  fine  grain  and  even  tex- 
ture. It  is  of  bright  brick  red  color  and  works  easily.  It  is 
well  adapted  to  a  large  variety  of  combinations  in  structural 
work.  Grouse  College  at  Syracuse  University  is  from  the 
East  Longmeadow  quarries.  (See  Figs.  219  and  220.) 


Fig.  220. — National  Life  Insurance  Company's  building,  Montpelier, 
Vermont.  By  courtesy  of  V.  A.  Doty. 

Roxbury  Conglomerate. — This  stone  often  noted  as  the  Rox- 
bury  pudding  stone  occurs  in  Brookline,  Dorchester,  Roxbury, 
and  other  localities  around  Boston.  In  many  places  the  rock  is 
a  coarse  conglomerate  bearing  large  pebbles  of  quartz,  granite, 
melaphyre  and  felsite.  In  others  the  texture  is  sufficiently  fine 
to  permit  the  quarrying  and  dressing  of  the  stone  for  structural 
purposes  in  and  around  Boston.  The  paste  in  which  the  pebbles 
are  embedded  is  greenish  gray  in  color  and  durable. 

Michigan. — The  rain-drop  sandstone  is  quarried  at  Mar- 
quette  and  L'Anse  in  the  Upper  Peninsula.  It  is  of  medium 

16 


242  BUILDING    STONES   AND    CLAYS 

texture  and  brownish  red  color  often  spotted  with  gray.  The 
gray  spots  are  equally  durable  with  the  rest  of  the  stone  and 
produce  an  effect  that  is  not  altogether  unpleasing.  This  sand- 
stone as  well  as  that  quarried  on  the  eastern  coast  of  Lake  Supe- 
rior is  of  Potsdam  age.  The  latter  stone  is  very  hard,  compact 
and  heavily  bedded.  (See  Fig.  221.) 

Lake  Superior  Sandstone. — This  sandstone  is  quarried  at 
Jacobsville,  Keweenaw  Bay.  The  stone  is  of  even  texture  and 
bright  red  color.  The  Mining  School  building  at  Houghton, 
Michigan,  and  the  basement  of  the  Cornell  University  Library, 
Ithaca,  N.  Y.,  are  from  this  stone.  Quarries  are  also  operated 


Fig.  221. — Rain-drop  sandstone,  Marquette,  Michigan.  Photo,  by 
C.  H.  Richardson. 

in  Eaton  and  Jackson  Counties  in  the  Carboniferous  formations 
of  the  southern  part  of  the  state. 

Minnesota. — According  to  N.  H.  Winchell  the  Kettle  River 
sandstone  is  one  of  the  most  important  building  stones  of  the 
state.  The  stone  is  of  fine  grain  and  even  texture  and  of  light 
pink,  brown  or  reddish  brown  color.  (See  Fig.  222.) 

A  very  hard,  compact  and  red  quartzite  occurs  in  Cotton- 
wood,  Pipestone,  Rock  and  Watonwon  Counties.  The  best 
known  quarries  are  at  New  Ulm.  A  deep  red  sandstone  is 
quarried  in  Nicollett  County  and  a  light  colored  sandstone  in 
Scott  County. 

Mississippi. — Sandstones  of  buff  and  gray  colors  and  of  fine 


SANDSTONES 


243 


grain  and  even  texture  are  known  to  occur  in  the  state.  Their 
use  is  only  local. 

Missouri. — In  Carroll  and  Johnson  Counties,  near  Miami 
and  Warrensburgh,  there  are  quarries  of  light  gray  sandstone 
that  weathers  well  and  has  been  used  in  several  important 
structures  in  the  state. 

Montana. — About  fifteen  counties  in  Montana  are  sandstone 
producers.  According  to  A.  C.  Peale  the  quarries  in  Gallatin 
County  produce  a  fine  grained,  even  textured,  light  gray  Cre- 
taceous sandstone.  Blocks  of  large  dimensions  can  be  ob- 
tained. The  stone  works  easily  when  first  quarried  but 


Fig.  222. — Kettle   River   sandstone,   Sandstone,    Minnesota, 
by  C.   H.   Richardson. 


Photo. 


hardens  on  exposure.  Yellowstone  County  produces  a  fine 
textured,  bluish  gray  sandstone  of  considerable  importance. 
It  is  found  in  the  Capitol  building  at  Helena,  Montana.  A 
compact  red  quartzite  is  also  quarried  near  Salesville. 

Nebraska. — In  this  state  Dakota  County  furnishes  a  very 
hard  compact  Cretaceous  quartzite  well  suited  for  structural 
purposes,  and  Memaha  County  supplies  a  fine  grained  flag- 
ging stone  for  local  consumption. 

Nevada. — Sandstones  are  not  extensively  quarried  in 
Nevada.  A  friable  coarse  textured  stone  of  gray  color  is 
quarried  to  some  extent  at  Carson  and  used  locally.  It  is  very 
soft  and  porous. 


244  BUILDING    STONES   AND    CLAYS 

New  Jersey. — Belts  of  sandstone  traverse  this  state  in  a 
northeasterly  direction  from  the  Delaware  River  to  the  New 
York  boundary.  J.  V.  Lewis  classifies  the  arenaceous  rocks 
as  follows:  (1)  A  belt  of  fine  grained,  even  textured  sand- 
stone, white,  gray,  brown  and  red  in  color.  They  are  gener- 
ally arkose  with  a  cement  of  silica,  or  silica  and  the  oxides  of 
iron.  They  are  compact  and  show  little  tendency  to  scale. 
(2)  A  belt  of  sandstone  and  conglomerates  in  the  Kittatinny 
Mountains.  (3)  A  quartzite,  shading  from  white  to  gray  in 
color  in  the  northwestern  part  of  the  state.  (4)  A  bluish 
gray,  purple  and  red  argillaceous  sandstone  near  Byram,  Law- 
renceville  and  Princeton.  (5)  Sandstones  suitable  for  flag- 


Fig.  223. — A  residence  at  Princeton,  New  Jersey,  built  of  Princeton 
argillite.  By  courtesy  of  J.  Volney  Lewis. 

ging  purposes  in  Hunterdon,  Sussex  and  Warren  Counties. 
Many  of  the  sandstones  of  New  Jersey  are  of  Triassic  age. 
(See  Fig.  223.) 

New  Mexico.— According  to  W.  G.  Tight  the  commercial 
sandstones  of  this  state  are  situated  in  the  vicinity  of  Albur- 
querque  and  Las  Vegas  Hot  Springs.  They  are  of  fine  grain 
and  even  texture.  They  shade  in  color  from  gray  to  pink. 

New  York. — The  Potsdam  sandstone  of  the  Raquette  river 
valley  in  St.  Lawrence  County  is  of  Cambrian  age.  It  is  the 
oldest  commercial  sandstone  in  the  state.  Its  texture  is  fine 
grained  to  medium.  Its  color  apart  from  the  type  locality  is 
grayish  white  to  gray.  In  the  Potsdam  quarries  the  colors 
are  light  pink,  light  red  and  reddish  brown.  According  to 


SANDSTONES  245 

J.  C.  Smock  its  mineral  composition  is  silica  with  a  cement  of 
silica  filling  the  interstices  amongst  the  sand  grains  and  bear- 
ing enough  of  the  oxides  of  iron  to  give  the  stone  its  charac- 
teristic tints.  It  is  one  of  the  strongest  and  most  durable  of 
all  known  sandstones.  Representatives  of  this  stone  may  be 
seen  not  only  in  a  large  number  of  buildings  in  Potsdam,  N.  Y., 


Fig.  224. — Block  of  Potsdam  sandstone,  Potsdam,  New  York,  show- 
ing tooled  surface.     Photo,  by  C.   H.   Richardson. 

but  also  in  the  Florence  Flats,  Syracuse,  N.  Y.,  All  Saints 
Cathedral,  Albany,  N.  Y.,  and  in  the  Dominion  Parliament 
buildings,  Ottawa,  Canada.  Smock  also  cites  quarries  of  the 
Potsdam  sandstone  at  Clayton  in  Jefferson  County,  Fort  Ann 
and  Whitehall  in  Washington  County,  Hammond  in  St.  Law- 
rence County,  Keeseville  in  Clinton  County,  Malone  in 


246  BUILDING    STONES   AND    CLAYS 

Franklin  County,  and  Port  Henry  in  Essex  County.  One  of 
the  most  notable  of  the  recent  structures  containing  Potsdam 
sandstone  is  the  new  Armory  at  Rochester,  N.  Y.  (See  Fig. 
224.) 

Hudson  River  Group. — The  sandstones  of  the  Hudson  River 
Group  are  of  quality  inferior  to  the  Potsdam  sandstone.  The 
stone  at  Aqueduct,  Schenectady  County,  is  fine  grained  and 
gray  to  blue  in  color.  The  fine  grained  and  bluish  sandstone 
of  Schenectady  may  be  seen  in  the  Memorial  Hall  at  Union 


Fig.  225. — Block  of  red  medina  sandstone,  Medina,  New  York,  show- 
ing character  of  rift.  Photo,  by  C.  H.  Richardson. 

College,  Schenectady.  This  stone  has  also  been  quarried  at 
Camden  in  Oneida  County,  Highland  in  Ulster  County,  New 
Baltimore  in  Greene  County,  Rhinebeck  in  Dutchess  County, 
Troy  in  Rensselaer  County. 

Medina  Sandstone. — This  sandstone  received  its  name  from 
Medina,  Orleans  County,  where  the  formation  is  especially 
well  developed  and  where  characteristic  fossils  appear  in  the 
gray  beds.  The  stone  varies  from  fine  grained  to  medium  in 
texture  and  in  color  from  gray  to  red  and  variegated.  The 
gray  variety  is  popular  for  paving  stone,  curbing,  etc.,  while 


SANDSTONES 


247 


the  red  variety  is  well  adapted  for  structural  purposes.  It  has 
found  its  way  into  many  western  cities  and  is  very  durable. 
J.  C.  Smock  cites  additional  quarries  in  the  Medina  Group  at 
Albion,  Hindsburgh,  Holley,  Hulberton  and  Shelby  Basin  in 
Orleans  County,  at  Brockport  in  Monroe  County,  Camden  in 
Oneida  County,  Lockport  in  Niagara  County,  Granby  and 
Oswego  in  Oswego  County,  Sterling  in  Cayuga  County,  Wol- 
cott  in  Wayne  County.  (See  Fig.  225.) 

Clinton  Group. — Sandstones  have  been  quarried  in  the  Clinton 
group  of  sedimentaries  at  Higginsville  in  Oneida  County. 

Devonian  Sandstones. — The  term  Hudson  River  Bluestone  has 


Fig.  226. — A  slab  of  sandstone  from  the  Clarke-Conroy  quarry, 
Norwich,  New  York.  By  courtesy  of  the  Clarke-Conroy  Company. 

been  used  commercially  to  designate  the  fine  grained,  even 
textured  compact  sandstones  of  the  middle  and  upper  De- 
vonian. In  the  main  they  are  gray  or  bluish  gray  in  color  and 
have  found  use  for  paving  blocks,  curbing  and  flaggings. 

The  belt  of  Devonian  sandstones  100  miles  in  length  and  of 
varied  width  stretches  from  Albany  County  in  a  southwesterly 
direction  to  the  Delaware  River.  The  quarries  at  Dormans- 
ville  and  Reidsville  have  furnished  much  flagging  stone  for 
the  city  of  Albany.  Ulster  County  has  been  a  large  producer. 
The  towns  in  which  the  bluestone  has  been  quarried  are 
Hurley,  Kingston  and  Saugerties.  It  has  been  quarried  in  a 


248 


BUILDING    STONES   AND    CLAYS 


large  number  of  towns  in  the  valley  of  Rondout  creek  and  its 
tributaries. 

Another  economic  group  of  sandstones  mostly  in  the  upper 
Devonian,  stretching  in  an  east  and  west  direction  nearly 
across  the  state  has  been  quarried  in  Coventry,  Guilford, 
Norwich,  Smithville  Flats  and  South  Oxford  in  Chenango 
County ;  in  Cooperstown  and  Oneonta  in  Otsego  County  ;  in 
Ithaca  and  Trumansburgh  in  Tompkins  County ;  Penn  Yan, 
Yates  County;  Portage  in  Livingston  County;  Watkins  in 
Schuyler  County  and  Warsaw  in  Wyoming  County.  The 


Fig.  227. — Block  of  Norwich  bluestone,  Oxford,  New  York,  show- 
ing planed  surface.  Photo,  by  C.  H.  Richardson. 

Warsaw  bluestone  is  extremely  fine  textured  and  dresses 
easily.  It  is  especially  well  adapted  for  structural  work  and 
trimmings.  The  Chapel  of  the  University  Avenue  Methodist 
Church,  Syracuse,  N.  Y.,  is  from  this  stone.  (See  Figs.  226, 
227  and  228.) 

Chemung  Group. — The  Chemung  group  furnishes  a  few  sand- 
stones for  local  consumption.  The  stone  as  a  rule  is  fine 
grained  and  even  textured.  In  color  it  shades  from  gray  to 
blue.  Quarries  have  been  worked  at  Corning  in  Steuben 
County,  Dansville  in  Livingston  County,  Elmira  in  Chemung 


SANDSTONES  249 

County,  Jamestown  in  Chautauqua  County,  Olean  in  Cat- 
taraugus  County  and  Waverly  in  Tioga  County. 

Triassic. — The  red  sandstones  of  Triassic  age  have  been  quar- 
ried largely  for  local  use  in  Haverstraw  and  Nyack,  Rockland 
County. 

North  Carolina. — This  state  quarries  Triassic  sandstones  of 
fine  grained  even  texture  and  of  gray,  brown,  reddish  brown 
and  red  colors.  The  Wadsborough  dark  brown  sandstone  that 
has  been  used  for  structural  purposes  in  Washington  is  per- 


Fig.    228.  —  Dressed    block    of    Warsaw    bluestone,    Warsaw,     New 
York,  showing  margin  of  drove  work.     Photo,  by  C.  H.  Richardson. 

haps  the  best  known  of  the  sandstones  of  the  state.    (See  Fig. 


Ohio.  —  According  to  E.  Orton  the  Berea  sandstone  is  a  very 
fine  grained,  even  textured  and  evenly  bedded  stone  of  gray, 
bluish  gray  and  buff  colors.  Slabs  150  feet  in  length,  5  feet 
in  width  and  only  3  inches  in  thickness  are  reported  to  have 
been  raised  intact  from  the  quarry  floor.  The  stone  bears  but 
little  cementing  material.  It  consists  of  grains  of  sand  held 


250  BUILDING    STONES   AND    CLAYS 

together  by  cohesion  induced  by  the  pressure  to  which  they 
were  subjected  at  the  time  of  their  consolidation.  The  Buena 
Vista  sandstone  in  the  southern  part  of  the  state  is  also  im- 
portant. 

Euclid  Blitcstonc. — This  stone  is  extensively  quarried  at 
Euclid  and  Newburgh,  Cuyahoga  County.  It  is  of  finer  grain 
and  of  more  compact  structure  than  the  Berea  grit.  It  is  of 
brown  color  near  the  surface  due  to  the  oxidation  of  an  iron 
content  but  a  dark  bluish  gray  color  beneath  the  surface. 

Oregon. — A  fine  grained,  dark  bluish  gray  sandstone  is 
quarried  near  Oakland  in  Douglas  County  and  a  fine  grained 
sandstone  near  Portland  in  Clackamas  County.  These  stones 
are  used  largely  for  structural  and  paving  purposes  in  many 
cities  writhin  the  state. 


Fig.  229. — Block  of  reddish  brown  sandstone,  Sanford,  North 
Carolina.  Photo,  by  C.  H.  Richardson. 

Pennsylvania. — According  to  T.  C.  Hopkins  the  Triassic 
brownstones  of  Pennsylvania  so  far  as  they  are  commercially 
developed  are  confined  to  the  eastern  and  southeastern  part 
of  the  state.  The  New  Red  area  in  which  most  of  the  produc- 
tive quarries  are  located  extends  from  the  Delaware  River 
north  of  Trenton  in  an  irregular  and  broad  belt  west-south- 
west through  Bucks,  Montgomery,  Berks,  Chester,  Lebanon, 
Lancaster,  Dauphin,  York  and  Adams  Counties.  Many  other 
less  productive  sections  are  known.  The  sandstones  were 
deposited  in  a  comparatively  narrow  lake,  bay,  or  arm  of  the 


SANDSTONES  251 

sea,  which  in  a  general  way  was  parallel  to  the  present  coast 
line,  and  limited  by  the  older  rocks  on  either  side.  The  sand- 
stones are  associated  with  a  coarse  conglomerate  which  was 
deposited  by  rapid  streams  or  currents,  and  shales  which  were 
formed  in  comparatively  quiet  waters.  The  sandstones  are 
intermediate  between  the  conglomerate  and  the  shale. 

Hmnmelstown. — The  Hummelstown  brownstone  is  the  best 
known  and  most  extensively  quarried  sandstone  within  the 
state.  The  strike  of  the  formation  is  east  and  west  and  the 
dip  of  the  beds  45  degrees  to  the  north.  The  separate  layers 
vary  from  20  inches  to  20  feet  or  more  in  thickness.  The 
depth  of  the  whole  formation  is  several  thousand  feet.  The 
quarries  often  present  a  thickness  of  50  feet  of  good  brown- 
stone. 

The  texture  of  the  brownstone  is  fine  grained  and  even 
with  a  greater  uniformity  in  texture  and  color  than  any  other 
brownstone  in  the  United  States.  Hopkins  states  that  the 
texture  is  so  close  and  the  grains  so  fine  that  the  stone  takes 
a  very  smooth  finish.  One  quarry  produces  a  purplish  brown 
while  all  the  others  produce  a  reddish  brown  stone  of  brighter 
and  warmer  shade  than  the  average  New  England  brown- 
stone.  The  stone  consists  of  fine  angular  quartz  grains  in  a 
cement  of  clay  and  iron  oxide,  and  is  one  of  the  most  durable 
brownstones  of  the  world.  (See  Fig.  230.) 

Mauch  Chunk. — There  is  a  belt  of  red  shale  and  quartzite  that 
stretches  from  the  Susquehanna  River  in  a  northeasterly 
direction  to  Mauch  Chunk  and  Scranton  that  has  furnished  a 
few  sandstone  quarries  whose  products  have  found  local  uses. 

South  Dakota. — According  to  N.  H.  Winchell  the  Sioux 
Falls  quartzite  is  a  fine  grained,  even  textured  stone  of  pink 
and  red  colors  that  receives  a  high  polish  and  is  equally  well 
adapted  for  structural  and  ornamental  work.  Mineralogically 
considered  the  stone  consists  of  quartz  grains  with  a  cement 
of  s'ilica,  and  only  enough  iron  oxides  present  to  impart  the 
characteristic  colors.  It  is  practically  impervious  to  moisture 
as  the  interstices  between  the  sand  grains  have  been  completely 
filled  by  the  cement.  Its  compression  test  is  very  high  for 
arenaceous  rocks,  25,000  pounds  to  the  inch.  The  stone  is 
represented  in  the  buildings  of  Grinnell  College,  Grinnell, 
Iowa,  and  in  the  German-American  Bank  and  Union  Depot 
at  Saint  Paul,  Minnesota. 

Tennessee. — This  state  produces  a  coarse  grained  gray 
sandstone  at  Parksville  and  a  coarse  grained  buff  and  pink 
sandstone  at  Sewanee. 


BUILDING    STONES   AND    CLAYS 


Fig.  230. — Pettier  and  Stymus  building,  New  York  City,  showing 
the  use  of  Hummelstown  brownstone  in  brownstone  fronts  (entire 
front  of  dressed  brownstone).  Photo,  by  T.  C.  Hopkins. 


SANDSTONES 


253 


Texas. — According  to  W.  B.  Phillips  excellent  sandstones 
occur  in  many  counties  in  Texas.  They  are  especially  abun- 
dant in  Bexar,  Burnet,  Lampasas,  Lavaca,  Tyler  and  Ward 
Counties. 

One  of  the  best  gray  sandstones  in  the  state  occurs  on  both 
sides  of  the  Colorado  River  at  Chaddi:k's  Mills  in  Lampasas 
County.  The  most  of  the  sandstones  of  Texas  are  of  clear 
gray  color.  Near  Barstow  in  Ward  County  there  is  a  good 
quarry  of  a  reddish  brown  sandstone  that  has  been  used  to  a 
considerable  extent.  One  of  the  more  recent  buildings  to  em- 


Fig.  231. — Red  sandstone  quarry  near  Barstow,  Ward  County, 
Texas.  By  courtesy  of  W.  B.  Phillips. 

ploy  this  stone  is  the  Bexar  County  Courthouse,  San  An- 
tonio, Texas.  (See  Fig.  231.) 

Utah. — The  Triassic  red  sandstones  of  Red  Butte  are  quar- 
ried to  some  extent  and  used  for  structural  purposes  in  Salt 
Lake  City. 

Virginia. — The  Triassic  sandstones  of  Maryland  extend 
southward  into  Virginia  and  have  been  quarried  to  some 
extent  near  Alanassas.  Near  Acquia  Creek  Juro-Cretaceous 
sandstones  have  been  quarried  for  some  of  the  public  buildings 
in  Washington,  D.  C. 


254  BUILDING    STONES    AND    CLAYS 

Washington. — According  to  W.  F.  Geiger  the  High  School 
Building  of  Seattle  represents  a  fine  grained,  even  textured 
dark  colored  sandstone  that  is  very  pleasing  in  its  decorative 
effect.  The  sandstone  quarried  on  Chuchanut  Bay  is  fine 
grained,  even  textured,  and  of  bluish  gray  color.  It  is  repre- 
sented in  the  United  States  Custom  House  at  Portland, 
Oregon. 

West  Virginia. — According  to  E.  Orton  the  commercial 
sandstones  of  the  state  are  of  Devonian  age,  fine  texture,  and 
bluish  gray  color. 

Wisconsin. — The  St.  Croix  sandstone  occurs  in  a  curved 
belt  that  stretches  from  the  St.  Croix  River  in  a  northeasterly 
direction  to  Menominee.  The  stone  varies  in  texture  from 
fine  grained  to  coarse,  and  in  color  it  is  white,  grayish  white 
and  light  buff. 

The  St.  Peters  formation  south  and  west  of  the  Menominee 
River  is  of  medium  and  coarse  texture,  and  of  white,  yellow, 
brown  and  red  colors.  (See  Fig.  232.) 


Fig.  232. — Port  Wing  brown  sandstone,  Port  Wing,  Wisconsin. 
Photo,  by  C.  H.  Richardson. 

FOREIGN    SANDSTONES 

Austria-Hungary. — According  to  J.  A.  Howe  Devonian 
sandstones  are  quarried  at  Trembola,  Galicia,  and  Sternberg 
in  Mahren.  Permian  and  Cretaceous  sandstones  are  quarried 
in  Bohemia. 


SANDSTONES 


255 


Belgium. — Devonian  sandstones  are  quarried  at  Hainault, 
Yvoir,  Gembloux  and  Wepion.  Carboniferous  sandstones  are 
obtained  from  the  Ardennes  and  Triassic  sandstones  at 
Luxembourg. 

British  Columbia. — Nanaimo  has  furnished  Cretaceous 
sandstones  for  buildings  in  Victoria,  and  New  Castle  Island 
provided  the  brownish  gray  sandstone  used  in  the  construc- 
tion of  the  United  States  Mint  at  San  Francisco. 

England. — Devonian  sandstones  occur  at  Devon  and  Corn- 
wall in  the  beds  of  the  Old  Red  Sandstone  series.  The  stone 
is  used  for  building  purposes  and  road  metal.  The  Carbon- 


Fig.    233. — Sawn    slab    of   banded   jasper,    Rhine    Valley,    Germany. 
Photo,  by  C.   H.  Richardson. 


iferous  Millstone  Grits  in  the  western  part  of  England  attain 
a  thickness  of  400  to  500  feet  and  furnish  many  fine  grained 
sandstones  for  structural  work.  The  Observatory  and  Wes- 
leyan  Memorial  Hall  at  Edinburgh  are  from  the  Northumber- 
land quarries. 

Ireland. — According  to  J.  Watson  the  Carboniferous  sand- 
stones of  Ireland  are  the  most  important  from  a  commercial 
standpoint.  They  are  of  even  texture  and  in  color  they  are 
white,  yellow,  red  and  purple.  The  Shamrock  sandstone  is 
gray  in  color  and  takes  a  fine  finish.  It  is  much  utilized  as  a 
building  stone. 

France. — According  to   J.   A.    Howe    sandstones   of   varied 


256 


BUILDING    STONES   AND    CLAYS 


texture  and  color  are  quarried  in  the  Silurian,  Carboniferous, 
Permian,  Triassic,  Cretaceous  and  Miocene  formations. 

Germany. — According  to  J.  Watson  the  picturesque  crags 
of  the  Saxon  Switzerland,  forming  the  great  gorge  of  the 
Elbe,  furnish  upper  Cretaceous  sandstones  of  fine  grain  and 
yellowish  drab  color  that  are  extensively  used  for  building 
purposes  in  Silesia.  Triassic  sandstones  are  quarried  in 
Wendelstein,  Zeil,  Heilbronn  and  elsewhere.  Permian  sand- 
stones are  quarried  at  Eggenstedt,  Saxony,  and  Liassic  sand- 
stones in  Franconia.  (See  Fig.  233.) 


Fig.    2:54 — Dougherty    quarry    in    Oneida    conglomerate,    Frankfort 
ill,   near  Utica,   New  York.     Photo,  by  M.   C.   Collister. 


Hill 


India. — The  valley  of  the  Ganges  furnishes  many  fine 
grained,  even  textured  sandstones  from  the  Vindhyan  forma- 
tions. The  prevailing  colors  are  gray,  yellow,  yellowish  red 
and  red.  They  are  represented  in  many  of  the  finest  buildings 
of  India.  It  is  equally  adapted  for  pierced  work  and  delicate 
carving. 

New  Brunswick. — The  finest  sandstones  of  New  Brunswick 
are  of  Lower  Carboniferous  age  and  occur  abundantly  in 
Albert  and  Westmoreland  Counties.  These  stones  are  of  fine 
grain  and  even  texture.  They  are  of  light  gray,  yellow,  red 
and  olive  green  color.  They  work  easily  and  have  been  im- 


SANDSTONES 


257 


ported  into  the  United  States  to  a  considerable  extent  for 
structural  work. 

Nova  Scotia. — The  sandstones  of  Nova  Scotia  near  the  head 
of  Pictou  Harbor  are  also  of  the  same  age  as  those  in  New 
Brunswick  and  possess  the  same  general  characteristics.  They 
are  not,  however,  so  extensively  quarried  and  imported  into 
the  United  States.  Bright  red  sandstones  occur  near  the  head 
of  the  Bay  of  Fundy. 

Ontario. — A  fine  grained,  even  textured  sandstone  of  Pots- 
dam age  is  quarried  on  Vert  Island  in  the  northern  part  of 


Fig.  235. — Rogers  quarry,  Cobleskill,  New  York,  showing  the  sand- 
stone beds  and  the  thickness  of  the  glacial  till.  Photo,  by  J.  F. 
France. 


Lake  Superior.  The  stone  is  of  bright  reddish  brown  color 
and  occurs  in  inexhaustible  quantities.  The  mineralogical 
content  of  the  stone  consists  of  quartz,  and  feldspar,  with  a 
few  scales  of  mica,  and  a  cement  of  the  oxides  of  iron. 

Quebec. — Ordovician  sandstones  occur  at  Point  Levis ;  they 
are  of  fine  grain,  grayish  green  color  and  durable. 

Scotland. — The  Devonian  old  red  sandstones  occupy  large 
tracts  in  Scotland.  They  present  a  wide  variety  of  texture 
and  color.  They  are  largely  used  for  structural  and  paving 
purposes.  One  peculiar  variety  is  described  by  R.  I.  Murch- 
ison  as  follows :  "The  Flagstones  of  Caithness  are  in  many 
17 


258 


BUILDING    STONES   AND    CLAYS 


places  impregnated  with  bitumen,  chiefly  resulting  from  the 
vast  quantity  of  fishes  embedded  in  them.  The  most  durable 
and  best  qualities  of  flagstone  are  derived  from  an  admixture 
of  this  bitumen,  with  finely  laminated,  siliceous,  calcareous, 
and  argillaceous  particles,  the  whole  forming  a  natural  cement 


\ 


Fig.  236. — Quarry  of  the  American  Bluestone  Company,  Warsaw, 
New  York,  showing  fractures  in  the  west  wall  of  the  quarry  and 
thickness  of  benches.  Photo,  by  W.  A.  Sargent. 


more  impervious  to  moisture  than  any  stone  with  which  I  am 
acquainted/' 

Craigleith  Sandstone. — The  Craigleith  sandstone  has  been  ex- 
tensively quarried  for  many  years  about  3  miles  from  the  city 
of  Edinburgh.  It  is  fine  grained,  even  textured,  and  of 
grayish  drab  color.  The  British  Museum  and  the  Bank  of 


SANDSTONES 


259 


England  in  London  show  the  adaptability  of  this  stone  for 
structural  work. 

Hailes  Sandstone. — This  sandstone  has  been  extremely  popu- 
lar in  Edinburgh  for  structural  work.  This  stone  is  also  of 
fine  grade  and  shows  three  distinct  colors,  white,  pink  and 
blue. 

Triassic. — The  Triassic  rocks  of  Scotland  furnish  at  Dum- 
iriesshire  a  medium  grained,  bright  red  sandstone  that  is  im- 
ported somewhat  into  the  United  States  for  structural  work. 


I 

Pri- 

dt 


Fig.  237. — Quarry  in  brownstone,  Hummelstown,  Pennsylvania. 
Photo,  by  T.  C.  Hopkins. 

The  Corncockle  quarries  from  Dumfriesshire  furnish  a  fine 
grained,  even  textured  sandstone  of  light  terra  cotta  red  color. 
The  Gatelaw  Bridge  quarries  produce  a  bright  red  sandstone 
that  has  also  been  extensively  imported.  The  Corsehill 
quarries  near  Annan  have  been  extensively  operated  and  their 
products  shippd  to  the  United  States  as  ballast  by  vessels 
sailing  from  Carlisle,  England,  and  commercially  recognized 
t-.s  Carlisle  sandstones. 

South  Africa. — The  famous  Rosetta  stone  takes  its  name 
from  the  district  of  Rosetta,  where  most  of  the  quarries  are 
situated.  It  is  fine  grained,  even  textured,  and  of  greenish 


BUILDING    STONES   AND    CLAYS 


gray  color.  It  is  extremely  popular  with  architects  of  Natal 
as  a  structural  and  decorative  stone.  The  Rosetta  stone  be- 
longs to  the  Ecca  formations  which  are  of  Permian  age. 

Triassic. — The  Forest  sandstone  of  Rhodesia,  according  to 
F.  P.  Mennell  is  extensively  developed  and  quarried  in  the 
Province.  The  stone  is  fine  grained  and  presents  two  varie- 
ties of  color.  One  is  a  rich  salmon  tint  and  the  other  a  delicate 
pink  color. 

INDUSTRIAL    FACTS    ABOUT    SANDSTONES 

Quarrying    Sandstones. — The    method    used    in    quarrying 


Fig.   238. — Mill   and   yard   of   the    Clark-Conroy   Company,    Norwich, 
New    York.      By    courtesy    of    the    Clark-Conroy    Company. 

sandstones  depends  somewhat  upon  the  character  of  the  joint 
planes  and  the  thickness  of  the  beds.  In  thin  bedded  sand- 
stones that  adhere  feebly  to  the  underlying  sheets  blocks  of 
the  desired  size  may  be  obtained  with  drills  and  wedges.  In 
some  instances  the  channelling  machine  is  used  to  cut  vertical 
channels  in  the  various  beds  as  has  already  been  described  in 
the  quarrying  of  marbles.  Where  the  blocks  are  thick  bedded 
holes  are  sometimes  drilled  10  inches  in  diameter  and  20  feet 
deep.  About  50  pounds  of  powder  in  an  oval  tin  canister  vvith 


SANDSTONES 


261 


unsoldered  edges  and  ends  covered  with  paper  or  cloth  is 
lowered  into  the  hole  and  placed  so  that  a  plane  passing 
through  its  edges  is  in  the  direction  of  the  desired  break  and 
then  fired.  The  loosened  blocks  are  then  split  into  smaller 
dimensions  by  wedges. 

The  Knox  system  consists  essentially  of  making  a  series  of 
elongated  holes  along  the  line  of  the  desired  break,  putting  in 
a  light  charge  of  powder,  leaving  an  air  chamber  between  the 
powder  and  the  confining  plug,  and  firing  all  simultaneously 
with  an  electric  battery.  It  requires  a  special  reamer  for  the 
elongation  of  the  drill  hole. 


Fig.  239. — Dimension  blocks  of  sandstone  from  Rogers  quarry, 
Cobleskill,  New  York,  designed  for  constructional  work  in  New 
York  City.  Photo,  by  C.  H.  Richardson. 

The  Lewis  system  consists  of  drilling  two  holes  about  half 
an  inch  apart,  cutting  out  the  rock  between  the  two  holes, 
filling  with  powder  and  blasting  in  the  same  manner  as  in  the 
Knox  system. 

The  Githens  system  drills  the  hole  with  a  single  drill \'m  the 
oval  shape  desired.  The  stone  is  then  blasted  as  in  the  pre- 
ceding systems. 

Whatever  the  system  of  blasting  may  be  there  is  always 
some  danger  of  loss  of  material  through  fractures  induced  by 
blasting.  The  heavier  the  charges  of  powder  used  the  greater 
this  danger  becomes.  Sometimes  these  planes  are  not  noticed 


262  BUILDING    STONES   AND    CLAYS 

until  the  stone  is  dressed,  or  even  set  in  its  bed  in  structural 
work,  yet  in  all  cases  such  fractures  are  lines  for  the  invasion 
of  moisture  and  the  stone  disintegrates  or  crumbles.  The  less 
jar  a  sandstone  receives  from  heavy  hammers  the  greater  will 
be  its  durability.  (See  Figs.  234,  235,  236,  237,  238  and  239.) 

Uses. — W.  C.  Day  in  the  Stone  Industry  of  1894  gives  the 
following  summary  of  the  uses  of  sandstones : 

Foundations,  Superstructures  and  Trimmings. 
Solid  fronts,  foundations,  cellar  walls,  underpinning,  steps, 
buttresses,  window  sills,  lintels,  kiln  stone,  capping,  belting 
or  belt  courses,  rubble,  ashlar,  forts,  dimensions,  sills. 

Street  Work. 

Paving  blocks,  curbing,  flagging,  basin  heads  or  catchbasin 
covers,  stepping  stones,  road-making,  macadam,  telford,  con- 
crete, sledged  stone,  crushed  stone. 

Abrasive  Purposes. 

Grindstones,  whetstones,  oilstones,  shoe  rubbers. 
Bridge,  Dam  and  Railroad  Work. 

Bridges,  culverts,  aqueducts,  dams,  wharf  stone,  break- 
waters, jetties,  piers,  buttresses,  capstone,  rails,  ballast,  ap- 
proaches, towers,  bankstone,  parapets,  docks,  bridge  covering, 
bridge  guards. 

Miscellaneous. 

Grout,  hitching  posts,  fence  wall,  sand  for  glass,  sand  for 
cement,  sand  for  plaster,  furnace  hearths,  lining  for  blast 
furnaces,  rolling-mill  furnkces,  lining  for  steel  converters,  fire 
brick,  silica  brick,  core  sand  for  foundries,  adamantine  plaster, 
cemetery  work,  millstones,  fluxing,  ganister,  glass  furnace, 
random  stock. 

Compression  Tests. — The  compressive  strength  of  sand- 
stones varies  widely.  Some  sandstones  are  extremely  friable  and 
with  insufficient  resistance  to  be  used  for  structural  purposes 
while  others  like  the  metamorphic  member  quartzite  are  supe- 
rior in  strength  to  most  of  the  granites.  A  few  of  the  tests 
from  widely  scattered  localities  are  appended  for  reference. 

Lbs.  Per  Sq.  In. 

1.  San  Jose,  California... 2,400 

2.  Haverstraw,    New    York 4,350 

3.  Riverside,    Indiana 6,800 

4.  Annan,   Scotland   7,925 

5.  Berea,    Ohio    10,250 

6.  Edinburgh,    Scotland    ...12,000 

7.  East   Longmeadow,    Massachusetts 12,210 


SANDSTONES  263 

8.  Kettle  River,  Minnesota  12,580 

9.  Albion,  New  York  13,500 

10.  Hummelstown,    Pennsylvania    13,610 

11.  Medina,  New  York  17,250 

12.  Warsaw,  New  York  19,022 

13.  Quartzite,  Sioux  Falls,  South   Dakota 25,000 

14.  Quartzite,    Pipestone,    Minnesota 27,750 

Analyses. — A  few  analyses  of  well  known  sandstones  are 

here  given  as  a  matter  of  reference. 
1.  Warsaw,  New  York,  bluestone. 

Silica,  SiO2  „ 76.50% 

Alumina,    A12O3 14.75 

Ferric  oxide,  Fe2O3 6.35 

Water,  H2O  2.00 


99.60 

2.  Hummelstown,  Pennsylvania,  brownstone. 

Silica,  SiO2 90.34 

Alumina,  A12O3 - 4.35 

Ferric  oxide,   Fe2O3 1.09 

Lime,  CaO  0.95 

Magnesia,  MgO  0.17 

Potash,  K9O t 1.30 

Soda,  Na2O 0.19 

Water,  H2O  0.61 

99.00 

3.  Riverside,  Indiana. 

Silica,  SiO2 93.16 

Alumina,  A12O3  1.60 

Ferric  oxide,  Fe2O3  2.69 

Lime,  CaO  ..  .  0.13 


97.58 
4.  Red  sandstone,  Barstow,  Texas. 

Silica,  SiO2  70.00 

Alumina,  A12O3  7.50 

Ferric  oxide,  Fe2O3  3.00 

Lime,  CaO  8.00 

Magnesia,  MgO  0.30 

Soda,  Na2O  2.00 

Potash,  K2O  2.50 

Carbonic  acid,  CO2  6.00 

Water,  H2O  " 0.40 

99.70 


264  BUILDING    STONES    AND    CLAYS 

5.   Craigleith  stone,  Edinburgh,  Scotland. 

Silica,  SiO2  98.30 

Alumina  and  ferric  oxide,  A19(X  and  Fe0Oo-.-        0.60 

Jo  Jo 

Calcium  carbonate,  CaCO3 1.10 


100.00 
6.  Red  Wilderness  Sandstone,  Gloucestershire,   England. 

Silica,  SiO2 88.70 

Alumina,  A12O3 3.25 

Ferric  oxide,  Fe,O3  1.<S0 

Ferrous  oxide,  FeO  0.30 

Manganous  oxide,  MnO 0.10 

Lime,  CaO 2,90 

Magnesia,    MgO 0.1 1 

Soda,  Na2O 0.31 

Carbon  dioxide,  CO,  ..  -  1.04 

Water,  H0O  ..  .......  0.59 


100.00 


SANDSTONES 


265 


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266  BUILDING    STONES   AND    CLAYS 

REFERENCES 

Becker,  G.  F.  Monograph  XIII,  U.  S.  Geological  Survey; 
Origin  of  Concretions,  Weathering,  Alteration  of  Sand- 
stones, 1888. 

Chamberlin,  T.  C.  Geology  of  Wisconsin,  Volumes  I  and  II ; 
Madison,  1883. 

Eckel,  E.  C.  Building  Stones  and  Clays ;  Wiley  and  Sons, 
New  York,  1912. 

Howe,  J.  A.  The  Geology  of  Building  Stones ;  E.  Arnold, 
London,  1910. 

Hopkins,  T.  C.  The  Carboniferous  Sandstones  of  Western 
Indiana,  1896. 

Hopkins,  T.  C.  The  Building  Materials  of  Pennsylvania 
Brownstones,  1896. 

Hull,  Edward.  A  Treatise  on  the  Building  and  Ornamental 
Stones  of  Great  Britain  and  Foreign  Countries ;  London, 

1872. 

Lewis,  J.  V.  Building  Stones  of  New  Jersey ;  New  Jersey 
Geological  Survey,  1908. 

Merrill,  F.  J.  H.  Building  Stones  of  New  York;  Mineral 
Industry,  Vol.  Ill,  1894. 

Merrill,  G.  P.  Stones  for  Building  and  Decoration ;  W^iley 
and  Sons,  1891. 

Ries,  H.  Building  Stones  and  Clay  Products ;  Wiley  and 
Sons,  1912. 

Smock,  J.  C.  Building  Stone  in  the  State  of  New  York;  Bul- 
letin III,  New  York  State  Museum,  1888. 

Smock,  J.  C.  Building  Stone  in  New  York ;  Bulletin  X,  New 
York  State  Museum,  1890. 

W^atson,  J.  Building  Stones ;  Cambridge  University  Press, 
1911. 

Winchell,  N.  H.  Building  Stones ;  Geology  of  Minnesota, 
Vol.  1,  Minneapolis,  1884. 

Zirkel,  Ferdinand.  Lehrbuch  der  Petrographie,  2nd  Edition, 
Vol.  Ill,  1894. 


CHAPTER  VI 

SHALE  AND  SLATE 
SHALE 

Definition. — A  shale  is  a  consolidated  mud  or  clay  in  which 
the  silicates  of  aluminum  are  the  most  important  and  character- 
istic constituents.  In  texture  it  is  fine  grained.  In  structure  it 
is  laminated  or  fissile.  The  term  shale  has  been  used  to  embrace 
a  wide  variety  of  sedimentaries  that  present  a  shaly  structure. 
Sand  grains  by  wave  action  may  be  reduced  to  an  impalpable 
powder  and  these  consolidated  flourlike  particles  may  present 
a  shaly  appearance.  In  the  presence  of  clayey  matter  such  rocks 
pass  into  argillaceous  sandstones.  Grains  of  calcite  may  be  ren- 
dered correspondingly  minute  and  consolidated  into  a  shaly  rock. 
In  the  presence  of  clayey  matter  the  stone  is  best  classified  as 
an  argillaceous  limestone. 

Varieties. — Many  varieties  arise  from  the  different  types  of 
detritus  from  which  the  shale  is  derived.  True  shales  pass  on 
the  one  hand  by  insensible  gradations  into  unconsolidated  clay 
beds  and  on  the  other  into  a  fissile  slate.  The  arenaceous  and 
calcareous  shales  have  already  been  mentioned.  Carbonaceous 
shales  are  often  associated  with  the  coal  measures  and  bear  a 
conspicuous  coaly  content.  A  bituminous  shale  is  one  rich  in 
volatile  hydrocarbons  and  from  which  various  oils  are  often  dis- 
tilled. A  pyritic  shale  is  one  containing  pyrite  or  marcasite.  An 
alum  shale  is  one  bearing  soluble  sulphates  that  result  from  the 
oxidation  of  the  pyrites  in  a  pyritic  shale.  A  kaolinitic  shale  is 
one  that  contains  kaolinite.  According  to  W.  M.  Hutchins 
kaolinite  is  present  only  in  small  quantities  in  some  of  the 
Carboniferous  clays  and  shales.  A  micaceous  shale  bears 
scales  of  mica  that  were  deposited  along  with  the  other  sedi- 
ments from  which  the  shale  was  derived.  The  occurrence  of 
the  brittle  micaceous  mineral,  chlorite,  derived  from  the  debris 
of  ferromagnesian  minerals,  gives  rise  to  a  chloritic  shale. 

Cements. — Cementation  is  a  subordinate  factor  in  the  forma- 
tion of  shales.  The  coherence  of  shale  is  due  mainly  to  the  pres- 
sure that  has  been  exerted  upon  the  colloidal  particles  contained 
in  the  mud  and  clays,  whose  consolidation  produced  shales.  Ac- 
cording to  C.  R.  Van  Hise  the  spaces  amongst  the  individual 
particles  is  reduced  to  a  minimum  and  the  porosity  of  the  stone 

267 


268  BUILDING    STONES   AND    CLAYS 

is  correspondingly  low.  In  this  respect  shales  bear  a  striking 
contrast  with  sandstones,  where  the  interstitial  spaces  exceed 
24  per  cent.  By  pressure  the  water  of  the  muds  is  largely  ex- 
pelled so  that  the  resulting  shale  bears  less  ground  water  than 
the  original  clay  or  mud  and  is  more  hydrous  than  slate.  There 
are  however  exceptions  for  the  analysis  of  the  bituminous 
shale  of  Dry  Gap,  Georgia,  as  made  by  L.  G.  Eakins,  shows 
a  lower  water  content  than  the  black  slate  of  Slatington, 
Pennsylvania. 

Uses. — Shales  are  too  soft  and  friable  for  structural  work. 
They  are  not  sufficiently  fissile  for  roofing  purposes.  They  are 
utilized  to  some  extent  as  road  metal.  The  more  compact  forms 
have  found  use  for  sidewalks  and  curbing.  Some  varieties  are 
used  in  the  manufacture  of  cement  and  bricks.  The  ferruginous 
shale  near  Mauch  Chunk,  Pennsylvania,  is  ground  and  used  as 
a  pigment.  Bituminous  shale  is  a  source  of  many  oils.  Shaly- 
coal  may  serve  as  an  unsatisfactory  fuel. 

Analysis. — The  following  represents  a  composite  analysis  of 
51  Paleozoic  shales,  by  H.  N.  Stokes. 

Silica,    SiO2    - 60.15 

Titanium  oxide,  TiO2 0.76 

Alumina,  A1,O3    " 16.45 

Ferric  oxide,  Fe2O3 4.04 

Ferrous  oxide,  FeO   2.90 

Manganous  oxide,   MnO    Trace 

Lime,  CaO   1.41 

Barium  oxide,  BaO 0.04 

Magnesia,    MgO    2.32 

Soda,   Na,0    1.01 

Potash,   K2O    3.60 

Lithia,  Li<,O    Trace 

Water,  H~O  +  110°F    3.82 

Water,   H2O— 110°F    0.89 

Phosphorus  pentoxide,  P2O5 0.15 

Carbon  dioxide,  CCX 1.46 

Sulphur  dioxide,  SO~    0.58 

Carbon,   C  '..  .   0.88 


100.46 

SLATE 

Definition. — Geologically  considered,  a  slate  is  a  meta- 
morphosed clay  or  shale.  It  may  or  may  not  have  paused  at  the 
shale  phase.  Commercially  a  slate  denotes  a  rock  which  pos- 


SHALE   AND    SLATE  269 

sesses  fairly  perfect  cleavage,  adapting  it  to  commercial  uses 
for  which  other  types  of  building  stones  are  not  well  suited.  In 
either  case,  with  few  exceptions,  its  mineral  composition  can  be 
distinguished  only  with  the  aid  of  the  microscope.  It  differs 
from  a  shale  in  that  it  has  perfect  cleavage  and  has  been  sub- 
jected to  a  considerable  amount  of  pressure.  Furthermore  a 
slate  is  somewhat  richer  in  silica  and  ferrous  oxide  than  a  shale. 
This  also  implies  that  a  slate  has  been  subjected  to  different 
processes  of  metamorphism  or  else  to  further  processes  than  a 
shale.  It  differs  from  a  schist  in  that  the  slate  is  the  more 
fissile,  consists  of  finer  particles  and  does  not  possess  the 
wavy  structure  that  is  characteristic  of  the  latter  rocks.  Shales, 
slates  and  schists  may  have  originated  in  deposits  of  nearly 
identical  character  but  they  have  undergone  different  pro- 
cesses. By  metamorphism  a  slate  passes  into  a  schist. 

Origin. — The  vast  majority  of  commercial  slates  are  of  sedi- 
mentary origin.  Fine  grained  homogeneous  sediments  of  clayey 
composition  have  been  subjected  to  pressure  sufficiently  intense 
to  develop  the  characteristic  cleavage  of  slates.  The  finest  of 
detritus  was  deposited  in  comparatively  quiet  waters.  When 
such  material  consolidates  under  normal  conditions  a  shale 
results.  Such  a  rock  breaks  into  irregular  blocks  because  it  does 
not  possess  the  cleavage  system  of  slates.  When  such  rocks  are 
subjected  to  crustal  movements  that  exert  heavy  pressure  or  long 
continued  pressure  certain  important  physical  changes  are  in- 
duced which  are  more  important  in  slates  than  the  accompanying 
chemical  changes.  The  sediments  must  be  fairly  homogeneous 
for  it  is  obvious  that  the  fissility  of  slates  can  not  be  induced  in 
a  heterogeneous  material.  The  material  must  not  be  rich  in  sand 
for  sand  beds  do  not  possess  the  requisite  plasticity  for  slates. 
Neither  do  highly  calcareous  deposits  possess  this  property  of 
plasticity.  Such  sedimentaries  must  possess  also  a  uniformity  of 
chemical  composition.  That  such  is  the  case  is  readily  shown 
by  consulting  a  wide  variety  of  chemical  analyses  of  roofing 
slates. 

Igneous  Origin. — A  few  slates  are  of  igneous  origin.  Even 
here  there  are  two  widely  different  modes  of  formation.  ( 1 ) 
Slates  formed  by  the  consolidation  of  volcanic  ash.  These  ash 
beds  must  have  been  subjected  to  pressure  sufficient  to  induce 
the  slaty  cleavage.  The  green  slates  of  the  Lake  District,  Eng- 
land, are  of  this  origin.  (2)  Slates  formed  by  the  shearing  of 
igneous  rocks.  The  green  slates  near  Placerville,  California, 
are  of  this  type.  They  appear  as  narrow  bands  extending  from 


270  BUILDING    STONES   AND    CLAYS 

the  top  to  the  bottom  of  the  quarry  wall  while  the  main  mass 
of  the  quarry  wall  is  a  glossy  black  slate  of  sedimentary  origin. 

Composition. — As  has  already  been  noted  the  chemical  com- 
position of  roofing  slates  is  fairly  constant.  This  holds  true  of 
all  slates  of  sedimentary  origin.  The  total  silica  and  alumina 
content  of  47  analyzed  samples  was  78.76  per  cent.  Total  iron 
oxides,  7.40  per  cent.  Total  lime  and  magnesia,  .05  per  cent. 
Total  alkalies,  4.47  per  cent.  Total  water  and  carbon  dioxide, 
5.60  per  cent.  A  large  part  of  this  water  is  chemically  combined 
and  the  lime  is  present  as  a  carbonate  which  often  serv.es  as  a 
cement.  The  average  composition  of  igneous  slates  differs  some- 
what from  the  above  analyses.  They  are  generally  lower  in  their 
silica  content  and  average  higher  in  alumina  as  will  be  seen  in  the 
analyses  of  slate  cited  later  in  this  chapter. 

Mineralogical  Composition. — This  is  an  important  factor  in 
the  estimation  of  the  durability  of  roofing  slate,  and  therefore 
their  commercial  significance.  If  homogeneous  clayey  matter  is 
compressed  by  weight  or  pressure  and  cemented  by  the  carbon- 
ates of  lime  and  magnesia,  or  by  kaolin,  or  varying  compounds 
of  iron,  their  cleavage,  strength  and  elasticity  are  low.  If  by 
metamorphism  the  kaolin  and  feldspathic  particles  have  been 
transformed  into  scales  and  overlapping  fibers  of  mica  their  fis- 
sility,  strength  and  elasticity  are  correspondingly  high.  The 
former  are  called  clay  slates  and  the  latter  mica  slates.  The 
slate  of  Martinsburg-,  West  Virginia,  is  a  clay  slate  while  the 
purplish  slate  of  Fair  Haven,  Vermont,  is  a  mica  slate. 

Minerals  of  Slates.— T.  N.  Dale  in  Bulletin  275  of  the  U.  S. 
Geological  Survey  gives  the  following  classification  of  the 
minerals  of  slates. 

Clastic  minerals :  quartz  grains,  feldspar  grains,  zircon 
grains,  muscovite  scales,  kaolin,  magnetite,  granular  carbon- 
ates. Clastic  or  authigenous  minerals:  rutile  needles,  tourma- 
line. Authigenous  minerals  :  chalcedonic  quartz,  vein  quartz, 
muscovite  (sericite),  biotite,  chlorite,  pyrite,  magnetite,  hema- 
tite, calcite,  magnesite,  siderite,  rhodochrosite,  andalusite, 
barite,  gypsum,  talc.  Organic  minerals  :  carbonaceous  matter. 

Classification. — Origin  may  be  made  the  basis  of  classifica- 
tion. Slates  then  fall  into  (T)  Aqueous  sedimentary,  (2)  Igneous. 
The  first  may  be  subdivided  into  (A)  Clay  slates  (B)  Mica  slates. 
The  latter  class  may  be  subdivided  upon  the  permanency  of  color 
into  (1)  Fading  slates  which  bear  a  sufficient  amount  of  siderite 
to  cause  discoloration  upon  prolonged  exposure  to  the  corrosive 
agents  of  the  atmosphere.  Some  slates  bearing  carbonaceous 
matter  or  graphite,  others  bearing  chlorite,  or  hematite  and 


SHALE    AND    SLATE 


271 


chlorite  fall  into  this  class.  (2)  Unfading  slates.  These  do  not 
discolor  materially  upon  prolonged  exposure.  These  are 
graphitic,  hematitic,  chloride,  or  hematitic  and  chloritic.  The 
slates  of  igneous  origin  are  further  subdivided  into  ash  slates  and 
dike  slates. 

Impurities. — The  objectionable  impurities  are  often  calcite, 
magnesite,  dolomite,  siderite,  rhodochrosite,  pyrite,  magne- 
tite, andalusite,  staurolite  and  garnet.  Calcite  is  an  element  of 
weakness  in  a  slate  as  well  as  in  a  sandstone.  Siderite  causes  a 
slate  to  fade.  The  decomposition  of  rhodochrosite  supplies  the 
black  oxide  of  manganese.  The  last  five  minerals  in  the  list  cited 
are  much  harder  than  the  slate  and  tend  to  gapple  the  machinery 


Fig.  240. — White  quartz  veins  in  closely  .folded  and  faulted  slate, 
Coventry,  Vermont.  Photo,  by  C.  H.  Richardson. 

used  in  cutting  slate.  The  cleavage  is  around  the  minerals 
rather  than  across  them.  Inequalities  of  surfaces  result  from 
their  presence.  (See  Fig.  240.) 

Color. — The  prevailing  colors  in  slates  are  black,  gray,  green, 
ted,  purple  and  spotted.  The  black  color  is  due  to  carbonaceous 
matter  derived  from  various  marine  organisms  suffering  decom- 
position on  the  floor  of  the  sea  where  the  sediments  were  de- 
posited. The  green  slates  owe  their  color  to  the  chloritization  of 
micaceous  scales  deposited  with  the  original  muds  from  which 
the  slate  was  derived,  or  possibly  in  the  case  of  igneous  slates  to 
the  metamorphism  of  hornblende.  The  red  slates  owe  their  color 


BUILDING    STONES   AND    CLAYS 

to  the  dehydration  of  limonite  and  the  purplish  slates  to  the 
presence  of  both  hematite  and  chlorite.  The  spotted  slates  owe 
their  spots  to  the  reduction  of  ferric  oxide  to  ferrous  oxide 
through  the  agency  of  decaying  organisms  and  the  removal  of 
the  ferrous  compound  either  as  an  organic  salt  or  carbonate. 
Such  patches  are  usually  richer  in  calcite,  siderite,  rhodochrosite, 
silica,  and  pyrite.  They  are  less  resistant  to  decomposition  than 
slates  of  uniform  color.  (See  Fig.  9.) 

Importance  of  Color. — It  is  obvious  that  slates  for  roofing- 
purposes  should  be  of  uniform  color  and  permanent.  If  they  fade 
at  all  as  many  slates  do  the  fading  should  be  uniform.  Bluish 
slates  often  turn  gray  and  red  slates  may  become  brown  upon 
prolonged  exposure.  Green  slates  are  the  most  unreliable  for 
they  bear  decomposable  carbonates,  and  limonite  is  one  of  the 
products  of  such  decomposition.  The  oxidation  of  grains  of 
pyrite  and  marcasite  produces  unsightly  blotches.  Building 
specifications  cite  colors  as  well  as  sizes  and  new  colors  are 
hard  to  introduce. 

Structure. — Bedding  and  cleavage  are  two  important  factors 
in  the  slate  industry.  The  bedding  planes  were  approximately 
parallel  with  the  sea  floor  on  which  the  sediments  were  deposited. 
The  beds  may  be  thick  or  thin.  They  may  alternate  with  arena- 
ceous or  calcareous  beds.  They  may  be  uniform  or  of  different 
colors.  They  are  the  starting  point  in  a  slate  quarry  and  indicate 
where  slates  of  a  uniform  grade  may  be  encountered. 

Cleavage. — The  cleavage  in  slates  is  somewhat  analogous  to 
the  gneissoid  lamination  in  certain  granitic  rocks.  It  is  due  to 
the  intense  pressure  to  which  the  rock  mass  has  been  subjected, 
to  the  orientation  of  unequiaxed  particles  in  the  original  sedi- 
ments and  to  the  development  of  new  minerals  by  chemical  and 
mineralogical  processes.  The  cleavage  may  conform  with  the 
original  bedding  planes,  in  which  case  the  split  surface  will  be 
rough,  or  it  may  diverge  at  any  angle  from  the  bedding  planes. 
E.  C.  Eckel  considers  this  divergence  in  the  majority  of  com- 
mercial slates  as  very  small.  The  lowest  angle  noted  by  T.  N. 
Dale  in  the  slates  of  Pennsylvania  was  from  5  to  10  degrees  and 
in  western  Vermont  and  eastern  New  York  20  degrees.  In  one 
quarry  in  central  Vermont,  as  observed  by  the  author,  it  was  85 
degrees. 

There  is  also  a  slip  cleavage  that  must  not  be  confused  with 
the  true  slaty  cleavage.  The  former  is  called  a  false  cleavage  or 
bate  by  the  quarrymen.  It  is  subsequent  in  origin  to  the  slaty 
cleavage  and  may  be  developed  in  one  or  more  than  one  system 


SHALE    AND    SLATE  273 

of  movements.  The  true  cleavage  pervades  the  entire  mass  and 
is  visible  in  each  fragment. 

Texture. — The  texture  of  slates  varies  widely.  Some  of  them 
are  very  fine,  some  fine,  some  medium,  while  others  are  coarse. 
For  mill  stock  a  slate  should  be  fine  grained,  rather  than  coarse, 
even  textured  rather  than  varied,  soft  rather  than  hard,  and  of 
uniform  rather  than  different  colors.  In  roofing  slate  durability 
and  strength  are  desired.  Uniformity  and  permanency  of  color 
?re  sought.  Such  slates  should  not  fracture  in  punching  the  nail 
holes. 

Specific  Gravity. — The  specific  gravity  of  roofing  slates 
varies  from  2.71  for  the  slate  of  Raceville,  New  York,  to  2.81  for 
the  Delabole,  Cornwall,  England,  slate. 

Transverse  Strength. — This  is  given  as  modulus  of  rupture 
in  pounds  per  square  inch.  It  varies  from  7,150  pounds  for  the 
Albion  quarry,  Pen  Argyl,  Pennsylvania,  to  11,250  pounds  for 
the  Peach  Bottom  slates  of  Pennsylvania  and  Maryland. 

AMERICAN  SLATES 

Arizona. — Near  Phoenix,  Arizona,  there  is  a  belt  of  bluish 
gray  slate  wrhich  is  approximately  one  mile  in  length  and  1,000 
feet  across  the  formation.  It  has  a  fair  degree  of  fissility  and 
bears  pyrite,  clayey  matter,  and  a  little  magnetite. 

Arkansas. — The  slate  belt  in  this  state  extends  from  near 
Little  Rock  in  a  westerly  direction  for  about  100  miles.  Its 
maximum  breadth  is  20  miles.  E.  R.  Buckley  gives  the  fol- 
lowing geological  section  of  the  area : 

Quartzite  and  sandstone 200  feet 

Red  slate  300  feet 

Quartzite  and  sandstone 500  feet 

Black   slate   400  feet 

Workable  roofing  slates  constitute  only  a  small  portion  of 
the  section.  Good  roofing  slates  are  obtained  near  Hot  Springs, 
Garland  County;  and* in  Montgomery  and  Polk  Counties  fine 
grained,  even  textured  slates  of  gray,  black,  red  and  greenish 
colors  are  manufactured.  These  slates  are  of  Ordovician  age. 

California. — According  to  E.  C.  Eckel  the  Mariposa  slates 
cover  a  large  area  in  Eldorado  County.  Their  general  strike 
is  north  15  degrees  west.  They  are  of  late  Jurassic  or  early 
Cretaceous  age.  The  main  mass  of  the  Eureka  quarry  product 
is  a  dense,  deep  black  slate,  splitting  very  finely  and  regularly, 
with  a  smooth  glistening  surface  much  like  that  of  the  Bangor 
and  Lehigh  slates  of  Pennsylvania.  The  frequency  of  ribbons 
18 


274  BUILDING    STONES   AND    CLAYS 

and  pyrite  nodules  prevents  the  slate  from  being  serviceable 
as  mill  stock,  but  as  roofing  material  it  is  excellent. 

The  Eureka  quarry  green  slate  is  of  igneous  origin.  It  was 
probably  derived  from  a  gabbro  or  similar  rock.  Eckel  states 
that  a  band  of  green  slate  several  feet  wide  crosses  the  Eureka 
quarry.  That  on  examination  he  found  that  the  borders  of  the 
band  were  not  parallel  to  the  ribbon  structure  of  the  black 
slate.  The  green  band  can  not,  therefore,  be  interbedded  with 
the  black  slates.  The  probability  that  it  represents  a  dike  of 
compact  igneous  rock  which  has  been  changed  to  slate  by 
pressure  subsequent  to  its  intrustion  is  strengthened  when  the 
chemical  composition  of  the  green  slate  is  considered.  The 
analysis  will  be  given  with  others  at  the  end  of  the  chapter. 
The  Eureka  quarries  have  shipped  their  products  to  Hawaii 
and  the  Island  of  Guam  while  the  slates  of  this  county  have 
no  competitor  in  the  markets  on  or  near  the  Pacific  coast. 

Georgia. — The  most  extensive  slate  quarries  in  the  United 
States  south  of  Pennsylvania  are  located  at  Rockmart, 
Georgia.  According  to  C.  W.  Hayes  the  Rockmart  slate  is  of 
Ordovician  age.  The  formation  which  now  produces  roofing 
slate  was  originally  a  fine  grained  homogeneous  clay  shale. 
Under  the  influence  of  metamorphism,  connected  probably 
with  the  extensive  faulting  which  the  region  has  undergone,  a 
very  perfect  cleavage  was  developed,  which  generally  obscures 
and  in  some  cases  obliterates  the  original  bedding.  Along  the 
Cartersville  fault  the  slate  near  the  fault  is  wrinkled  so  that 
it  does  not  cleave  readily,  and  at  a  considerable  distance  from 
the  fault  the  cleavage  is  only  imperfectly  developed.  There- 
fore, the  best  slates  are  encountered  within  a  comparatively 
narrow  area  from  one  to  five  miles  from  the  fault. 

The  better  grade  of  material  is  a  black  roofing  slate.  The 
product  commands  a  good  price.  The  Southern  States  Port- 
land Cement  Company  is  located  about  half  a  mile  east  of 
Rockmart,  Georgia.  This  company  is  using  the  poorer  grades 
of  slate  that  with  many  companies  becomes  waste  in  the  man- 
ufacture of  Portland  cement.  The  products  used  are  a  mixture 
of  slate  and  limestone. 

Maine. — Commercial  slates  are  found  in  Maine  in  Pisca- 
taquis  County  which  is  located  near  the  center  of  the  state. 
The  quarries  are  both  to  the  east  and  to  the  west  of  Sebec 
Lake  in  the  towns  of  Blanchard,  Brownville  and  Monson. 
According  to  C.  H.  Hitchcock  the  slate  formations  are  of 
Paleozoic  age.  The  belt  is  from  15  to  20  miles  in  width  and 
strikes  in  a  northeasterly  direction. 


SHALE   AND    SLATE 


275 


Blanchard. — The  quarries  of  the  Lowell  Slate  Company  are 
situated  at  North  Blanchard,  Maine.  The  Blanchard  quarry 
is  300  feet  long,  50  feet  wide  and  200  feet  deep.  The  slate 
beds  alternate  with  quartzites.  The  slate  is  a  very  dark  gray. 
It  is  of  fine  grained,  even  texture  and  slightly  lustrous.  It  is 
used  for  roofing,  mill  stock  and  electrical  appliances. 

Broivnville. — The  quarry  of  the  Merrill  Brownstone  Slate 
Company  is  situated  less  than  a  mile  from  Brownville  station 
and  to  the  west  of  Pleasant  River.  According  to  T.  N.  Dale 
there  are  in  this  quarry  42  beds  of  slate  alternating  with  as 
many  beds  of  quartzite.  The  total  thickness  of  these  beds  is 


Fig.  241. — Merrill  slate  quarry,  Brownville,  Maine.  The  end  wall 
working  face  has  42  beds  of  slate  alternating  with  quartzite.  By 
courtesy  of  the  U.  S.  Geological  Survey. 


165  feet.  At  the  Hughes  quarry  which  is  operated  by  the 
same  company  and  is  situated  about  a  mile  northwest  of  the 
Merrill  quarry  there  are  28  beds  of  slate  alternating  with  as 
many  beds  of  quartzite.  The  total  thickness  here  is  161  feet 
C  inches.  These  slates  are  very  dark  gray  in  color.  They  are 
fine  grained,  even  textured  and  with  bright  luster.  The 
product  is  used  largely  for  roofing  purposes.  The  presence  of 
magnetite  prevents  its  use  for  electrical  appliances.  (See  Fig. 
241.) 

Monson. — The   quarries   of   the   Monson    Slate   Company   are 


276  BUILDING    STONES   AND    CLAYS 

about  3  miles  southwest  of  the  village  of  Monson,  while  the 
quarry  of  the  Monson  Consolidated  Slate  Company  is  at  West 
Monson.  The  slates  are  of  dark  gray  color,  fine  grain,  even 
texture,  free  from  magnetite,  but  they  bear  a  little  graphite 
and  pyrite.  They  are  used  for  roofing  and  mill  stock.  The 
absence  of  magnetite  makes  them  desirable  for  electrical  ap- 
pliances. 

The  Forks  slate  quarry  is  in  Somerset  County  about  18 
miles  west  of  the  North  Blanchard  quarries.  The  slate  is  of 
bluish  black  color,  fine  texture,  perfect  cleavage  and  is  well 
suited  for  both  roofing  and  mill  stock  purposes. 

Maryland. — There  are  two  slate  districts  in  Maryland.  One 
lies  about  30  miles  northeast  of  Baltimore  and  the  other  about 
40  miles  west  of  Baltimore.  The  former  is  in  Hartford  County 
where  the  slate  at  Cardiff  is  continuous  with  the  Peach  Bottom 
slates  of  Pennsylvania.  The  slate  is  of  bluish  black  color,  fine 
grain,  smooth  texture,  tough  and  non-fading.  The  second 
district  is  located  in  Frederick  and  Montgomery  Counties, 
where  quarries  have  been  worked  to  some  extent.  This  stone 
is  also  of  bluish  black  color  and  good  quality.  The  Thurston 
and  Ijamsville  quarries  are  the  best  known.  They  bear  no 
magnetite  and  therefore  are  suited  for  electrical  appliances. 
E.  B.  Mathews  regards  them  as  bearing  talc  to  about  5  per 
cent. 

Massachusetts. — The  slate  quarries  at  Lancaster,  Worcester 
County,  were  opened  about  1750.  In  the  last  century  the 
quarrying  has  been  intermittent.  The  slate  is  durable  and 
essentially  a  roofing  slate.  According  to  N.  S.  Shaler  a  second 
slate  district  occurs  in  the  vicinity  of  Boston  and  Cambridge. 
Shaler  regards  this  stone  of  great  value  for  rough  building  and 
very  durable.  Shepherd  Memorial  Church  in  Cambridge  rep- 
resents this  slate.  The  material  has  also  been  used  extensively 
in  the  manufacture  of  permanent  roads. 

Michigan. — The  black  slates  of  Michigan,  quarried  in 
Houghton,  Marquette  and  Menominee  are  of  pre-Cambrian 
age  and  practically  inexhaustible  in  quantity.  They  are  black 
in  color  of  fine  grain,  even  texture,  tough,  durable  and  there- 
fore good  roofing  material.  Good  slates  have  also  been 
quarried  about  3  miles  from  Huron  Bay. 

Minnesota. — According  to  N.  H.  Winchell  there  is  an  inex- 
haustible supply  of  hard,  black,  and  apparently  durable  slate 
in  northern  Minnesota,  a  few  miles  west  of  Duluth.  Winchell. 
regarded  these  slates  as  suitable  for  all  uses  to  which  slate  is 


SHALE    AND    SLATE  277 

normally  applied.  T.  N.  Dale  regards  these  slates  of  inferior 
quality.  They  are  of  pre-Cambrian  age. 

New  Hampshire. — A  slate  belt  traverses  the  western  part  of 
the  state  in  a  line  roughly  parallel  with  the  Connecticut  River. 
Quarries  have  been  operated  in  Hanover,  Lebanon  and  Little- 
ton. The  product  from  the  Hanover  quarries  was  used  for 
roofing  and  rough  work.  The  Lebanon  quarries  are  in  the 
eastern  part  of  the  town.  The  stone  has  not  the  perfect 
cleavage  of  the  Maine  and  Vermont  slate.  It  sometimes  bears 
staurolites  that  interfere  with  the  splitting,  trimming  and 
planing  of  the  slate.  The  stone  has  been  used  for  many  kinds 
of  work  and  the  waste  product  ground  and  bolted  into  slate 
flour.  The  Littleton  slate  has  been  quarried  in  two  localities. 
The  productive  belt  is  about  600  feet  in  width,  but  it  must  not 
be  inferred  that  the  whole  600  feet  is  good  roofing  slate.  The 
stone  is  of  dark  blue  color  and  fairly  fissile.  Its  use  has  been 
for  roofing,  tables,  platforms,  curbs  and  flagstones. 

New  Jersey. — Near  Newton  and  Lafayette  the  eastern  ex- 
tension into  New  Jersey  of  the  Bangor-Slatington  slate  of 
Pennsylvania  has  furnished  good  roofing  material.  The  char- 
acteristics of  the  slate  are  given  under  the  caption  of  Penn- 
sylvania. 

New  York. — A  slate  belt  in  the  extreme  eastern  part  of  the 
state  traverses  in  a  northeasterly  direction  the  counties  of 
Columbia.  Dutchess,  Rensselaer  and  Washington.  The  pro- 
ductive quarries  are  in  Granville,  Hampton  and  Whitehall. 
Greenish  and  purplish  slates  of  Lower  Cambrian  age  were 
once  extensively  quarried  at  Middle  Granville  and  Jamesville 
on  the  New  York  side  of  the  line,  but  at  present  these  slates 
are  almost  exclusively  quarried  on  the  Vermont  side  of  the 
boundary  line.  The  Hudson  River  Group  furnishes  Ordo- 
vician  slates  of  red  and  green  colors.  It  is  on  the  New  York 
side  that  these  slates  reach  their  best  development. 

T.  N.  Dale  states  that  the  red  slate  is  of  a  decidedly  reddish 
brown  color,  becoming  brighter  on  exposure.  To  the  unaided 
eye  its  texture  is  fine,  and  its  cleavage  surface  varies  from 
slightly  roughish  to  speckled  with  minute  protuberances  that 
are  without  luster.  It  is  magnetitic,  calcitic,  argillaceous  and 
sonorous.  Dale  gives  the  mineralogical  composition  in  de- 
scending order  of  abundance,  muscovite  (sericite),  quartz, 
hematite,  calcite,  chlorite,  magnetite,  rhodochrosite.  These 
red  slates  are  permanent  in  color.  (See  Fig.  242.) 

The  bright  greenish  slate  is  interbedded  with  the  red  slate. 
Its  texture  is  much  like  that  of  the  red  and  its  green  color  is 


278  BUILDING    STONES   AND    CLAYS 

attributed  to  chlorite.  Ordovician  black  slates  have  been 
quarried  near  Hoosick  and  elsewhere  in  Rensselaer  County. 
Pennsylvania.  —  The  slate  producing  districts  of  Pennsyl- 
vania are  known  as  the  Bangor-Slatington  district  and  the 
Peach  Bottom  district.  The  former  is  located  in  Lehigh  and 
Northampton  Counties  and  the  latter  in  Lancaster  and  York 
Counties.  The  former  embraces  a  belt  32  miles  long  and  2  to 
4  miles  wide  on  the  south  side  of  Blue  Mountain.  It  stretches 
from  the  Delaware  Water  Gap  in  a  southwesterly  direction  to 
within  5  miles  of  Lehigh  Gap.  The  exposures  of  slate  and 
shale  formations  vary  from  1,000  to  6,000  feet.  These  terranes 


Fig.  242.  —  Small  slab  of  red  slate,  Granville,  New  York.  Photo,  by 
C.  H.  Richardson. 

are  of  Ordovician  age  but  more  specifically  they  belong  to  the 
Martinsburg  shale.  The  more  northerly  and  upper  portions 
of  the  beds  furnish  the  soft  vein  and  the  more  southerly  and 
lower  portions  supply  the  hard  vein.  The  quarries  at  Bangor, 
East  Bangor,  Danielsville,  Pen  Argyl,  Slatedale  and  Slatington 
are  in  the  soft  vein  belt,  'while  those  of  Belfast  and  Chapman 
are  in  the  hard  vein  belt. 

Bangor.  —  The  Bangor  quarries  are  1,000  feet  long,  500  feet 
wide  and  300  feet  deep.  The  slate  is  of  dark  gray  color,  of 
fine  grain,  of  perfect  cleavage,  and  without  luster.  It  is 
graphitic,  calcitic,  argillaceous,  sonorous  and  the  sawn  edge 
shows  pyrite.  The  quarries  at  East  Bangor  produce  a  dark 


SHALE    AND    SLATE 


279 


! 


Fig.  243. — Old  Bangor  slate  quarry,  Bangor,  Pennsylvania,  show- 
ing the  close  overturned  syncline  crossed  by  almost  horizontal 
cleavage.  By  courtesy  of  J.  S.  Moyer. 


Fig.  244. — Crown  slate  quarry,  Pen  Argyl,  Pennsylvania.  This 
quarry  has  been  a  large  producer  of  roofing  slate.  By  courtesy  of 
the  Pen  Argyl  Slate  Company. 


280 


BUILDING    STONES   AND    CLAYS 


bluish  gray  slate  that  in  all  other  respects  is  like  the  Bangor 
product.  (See  Fig.  243.) 

Pen  Argyl. — These  quarries  are  650  feet  long,  (500  feet  wide 
and  300  feet  deep.  They  are  nearer  the  bottom  of  the  soft 
vein  than  the  Bangor  slate.  The  slate  is  of  dark  gray  color, 
of  fine  texture,  while  the  cleavage  surface  is  slightly  rough  and 
almost  lusterless.  It  is  graphitic,  magnetitic  and  pyritic.  It 
contains  less  carbonate  than  the  slates  obtained  at  higher  alti- 
tudes on  the  soft  vein.  (See  Fig.  244.) 

Chapman. — The  Chapman  quarries  are  in  the  hard  vein  belt 


Fig.  245. — Blue  Mountain  slate  quarry  near  Slatington,  Penn- 
sylvania, showing  the  character  of  the  syncline,  its  relation  to  cleavage 
and  the  southward  bending  of  the  cleavage  at  the  surface.  By 
courtesy  of  the  U.  S.  Geological  Survey. 

and  therefore  lower  down  in  the  Ordovician  formations.  The 
quarries  are  about  800  feet  long,  200  feet  wide  and  300  feet 
deep.  The  slate  is  of  dark  gray  color,  fine  texture,  roughish 
cleavage  surface  and  somewhat  lustrous.  The  amount  of  car- 
bonate is  small  and  the  stone  weathers  well.  The  above  quarries 
are  all  located  in  Northampton  County. 

Slatington. — The  quarries  in  Lehigh  County  are  confined  to 
an  area  about  3  miles  square,  along  Trout  Creek  and  its  tribu- 
taries. Some  of  the  quarries  have  attained  a  depth  of  300  feet. 
The  Slatington  slate  is  of  dark  bluish  gray  color,  of  fine  grain, 


SHALE    AND    SLATE  281 

even  texture  and  nearly  lusterless.  There  is  little  if  any  pyrite 
present,  but  the  slate  bears  magnetite  and  graphite.  It  is  also 
calcitic  and  argillaceous.  (See  Fig.  245.) 

Peach  Bottom  Slate. — This  belt  forms  a  low  ridge  that  extends 
from  Lancaster  County,  Pennsylvania,  through  York  County 
to  Cardiff,  Maryland.  The  belt  is  10  miles  long  and  varies  in 
width  from  1,000  to  3,000  feet.  This  slate  is  of  dark  gray  color 
with  a  somewhat  bluish  tinge.  Its  texture  is  minutely  gran- 
ular and  crystalline.  It  contains  graphite,  magnetite,  pyrite 
and  is  non-calcitic.  It  is  very  sonorous  and  non-fading. 

Tennessee. — According  to  C.  L.  Keith  the  slate  deposits  are 
located  in  the  eastern  part  of  the  state.  Two  formations  are 
producers.  The  Wilhite  slate  is  too  calcareous  and  soft  for 
commercial  use  in  the  vicinity  of  Little  Tennessee  River,  but 
it  has  the  necessary  hardness,  evenness  and  cleavage  along 
Little  Pigeon  River.  Along  this  stream  the  slate  is  well  ex- 
posed over  great  areas,  yet  the  stone  has  not  been  developed 
on  a  commercial  basis. 

Keith  cites  quarries  in  the  Pigeon  slate  along  the  Little 
Tennessee  River  at  many  points.  Slates  and  flags  have  been 
quarried  for  local  use.  Quarries  have  been  opened  some  two 
miles  from  the  river  and  these  quarries  produce  slates  that  are 
of  fine  grain,  even  texture  and  well  suited  for  mill  stock  or 
roofing  purposes. 

Utah. — According  to  E.  C.  Eckel  the  Provo  slates  furnish 
green  and  purple  varieties,  the  latter  variety  being  present  in 
the  larger  quantity.  The  green  slates  show  less  tendency  to 
cleavage  than  the  purple  varieties  and  are  therefore  less  sat- 
isfactory for  roofing  purposes.  They  rub  smooth  and  make 
good  slabs  for  mill  stock.  The  purple  slate  splits  well  and 
shows  a  surface  about  as  smooth  as  that  of  the  Peach  Bottom 
slate  of  Pennsylvania  and  Maryland.  These  slates  are  sup- 
posed to  be  of  Ordovician  age  but  may  be  Cambrian. 

Vermont. — The  author  has  visited  every  known  slate 
quarry,  whether  actively  operated  or  abandoned,  in  Vermont, 
as  well  as  in  New  Hampshire  and  New  York.  The  work  of 
T.  N.  Dale  has  the  greater  value  on  account  of  the  larger 
element  of  time  and  the  greater  detail  he  has  given  his  results. 

There  are  four  distinct  slate  belts  in  Vermont  which  have 
some  commercial  significance. 

(1)  THE  CONNECTICUT  RIVER  SLATES. — This  belt  appears  in 
Guilford,  in  Windham  County,  in  the  extreme  southeastern  part 
of  the  state,  and  traverses  northward  interruptedly  nearly  the 
entire  length  of  the  state.  The  width  of  the  belt  varies  from 


282  BUILDING    STONES   AND    CLAYS 

100  to  1,000  feet.  Its  general  strike  is  north  10  degrees  east. 
In  North  Hartland,  in  Windsor  County,  it  is  north  and  south 
but  changes  in  Hartford,  in  the  same  county,  to  north  50  de- 
grees east.  The  dip  changes  from  60  degrees  west  in  Hart- 
ford to  85  degrees  east  in  Fairlee.  Quarries  have  been  worked 
in  Guilford  in  Windham  County,  Thetford  in  Orange  County 
and  Waterford  in  Caledonia  County.  The  slate  is  black  or  of 
very  dark  gray  color.  It  is  fine  grained,  medium  textured  and 
lustrous.  Waterford  slate  splits  in  blocks  of  any  dimension 
desired.  It  is  graphitic  and  several  samples  have  shown  no 
effervescence  \vith  cold  dilute  HC1.  The  quarry  was  abandoned 
on  account  of  distance  from  the  railroad.  The  slate  is  of  Or- 
dovician  age.  (See  Fig.  246.) 


Fig.  246. — Slab  of  clay  slate,  Waterford,  Vermont,  showing  the 
character  of  the  cleavage  surface.  Photo,  by  C.  H.  Richardson. 

(2)  THE  MEMPHREMAGOG  SLATES. — This  belt  appears  very 
narrow  in  Barnard  in  Windsor  County,  and  widens  to  the 
northward  to  about  7  miles.  It  extends  northward  to  Lake 
Memphremagog  a  distance  of  nearly  100  miles.  In  the  more 
northern  sections  there  are  three  distinct  belts  of  slate  with 
intervening  limestone.  The  strike  varies  from  north  10  de- 


SHALE    AND    SLATE  283 

grees  east  to  north  45  degrees  east.  Its  dip  is  at  a  high  angle 
to  the  west.  It  flanks  the  eastern  edge  of  the  Green  Mountain 
range  and  is  Ordovician  in  age.  This  slate  has  been  quarried 
in  Coventry  in  Orleans  County,  and  in  Montpelier  and  North- 
field  in  Washington  County. 

Montpelier. — The  old  Sabin  quarries  are  located  about  one-half 


Fig.  247. — Interior  of  Sabin  slate  quarry,  Montpelier,  Vermont, 
showing  cleavage  and  system  of  jointing.  Photo,  by  C.  H. 
Richardson. 

mile  east  of  the  city  of  Montpelier.  They  were  operated  by 
means  of  three  wide  openings  at  intervals  across  the  strike 
and  communicating  with  each  other  by  a  ten-foot  open  cut, 
which  also  served  as  a  drain.  The  strike  of  both  bedding  and 
cleavage  varies  from  north  15  degrees  east  to  north  20  degrees 
east  and  the  dip  from  70  degrees  to  75  degrees  west. 

A  large  percentage  of  waste  resulted  from  the  manner  in 


284  BUILDING    STONES   AND    CLAYS 

which  the  quarries  were  opened.  Secondary  quartz  veins  also 
increased  the  amount  of  waste.  These  facts  are  said  to  ex- 
plain why  the  quarries  are  now  idle.  (See  Fig.  247.) 

Northficld. — The  quarries  owned  and  operated  by  the  Vermont 
Black  Slate  Company  are  located  about  10  miles  south  10 
degrees  west  from  Montpelier  and  2  miles  south  of  Northfield. 
The  strike  of  the  bedding  varies  from  north  10  degrees  east 
to  north  15  degrees  east.  The  strike  of  the  cleavage  prac- 
tically coincides  with  that  of  bedding  but  dips  75  degrees  west. 
The  low  easterly  dipping  planes  as  shown  in  Fig.  249,  some- 
what resemble  a  secondary  cleavage,  while  the  steep  westerly 
ones  have  the  characteristics  of  bedding.  The  total  width  of 
the  slate  at  South  Northfield  exceeds  2,000  feet. 

At  the  quarries  of  the  Vermont  Black  Slate  Company  there 
are  no  ribbons  in  the  bedding  and  no  horizontal  joints  in  the 


Fig.  248. — Slab  of  clay  slate,  Northfield,  Vermont,  showing  perfect 
cleavage.  Photo,  by  C.  H.  Richardson. 

cleavage.  Therefore,  channelling  in  a  horizontal  direction  be- 
comes necessary.  On  account  of  these  factors  it  is  easier  to 
obtain  large  slabs  for  mill  stock  than  small  ones  for  roofing 
slates. 

The  slate  is  of  dark  gray  color  and  fine  texture.  Its  cleavage 
surface  is  smooth  and  lustrous.  It  contains  minute  crystals 
of  pyrite  with  their  longer  axis  pointing  in  the  direction  of  the 
grain.  It  also  contains  some  non-metallic  lenses.  It  is  slightly 
graphitic  and  magnetitic.  (See  Figs.  248  and  249.) 


SHALE    AND    SLATE 


285. 


(3)  THE  CAMBRO-ORDOVICIAN  BELT. — This  is  by  far  the  most 
important  slate  bearing  district  in  the  state.  It  furnishes  the 
well  known  green  and  purple  slates  of  large  commercial  sig- 
nificance. It  lies  between  the  Taconic  range  and  Lake  Cham- 
plain,  and  extends  from  the  town  of  Sudbury  in  Rutland 
County,  southward  to  Rupert  in  Bennington  County,  a  dis- 


Fig.  249. — Sabin  slate  quarry,  Northfield,  Vermont,  showing  the 
difference  between  the  cleavage  and  bedding  planes.  Photo,  by 
C.  H.  Richardson. 

tance  of  26  miles.  This  belt  also  passes  to  the  southwest  into 
Washington  County,  N.  Y.,  where  it  has  thus  far  proved  of 
less  economic  importance. 

Geological  Relations. — According  to  T.  N.  Dale  the  Ordovician 
(Berkshire)  schist  of  the  Taconic  range  is  bordered  on  the 
west,  except  for  about  6  miles  in  Pawlet  and  Rupert,  by  a  belt 
of  Lower  Cambrian  rocks  estimated  at  1,400  feet  in  thickness. 


286 


BUILDING    STONES   AND    CLAYS 


These  terranes  include  about  240  feet  of  greenish  and  purplish 
roofing  slates.  The  boundary  between  the  Ordovician  and 
the  Lower  Cambrian  rocks  represents  both  an  unconformity 
and  a  folded  overlap.  In  Pawlet  and  Rupert  the  schists  of  the 


I 


Fig.  250. — Rising  and  Nelson  slate  quarry,  Pawlet,  Vermont,  show- 
ing syncline  in  the  seagreen  slate.  Depth  100  ft.  By  courtesy  of 
the  U.  S.  Geological  Survey. 

Taconic  range  merge  at  the  west  through  decrease  in  meta- 
morphism  into  an  irregular  area  of  shales  and  grits  of  Hudson 
River  age.  These  terranes  are  1,200  feet  in  thickness  and  in- 
clude about  50  feet  of  commercial  reddish  and  greenish  slate. 
This  formation  has  long  been  quarried  in  Granville  and  Hamp- 


SHALE    AND    SLATE  287 

ton,  N.  Y.,  as  described  on  page  277.  In  some  instances  the 
Lower  Cambrian  slate  protrudes  through  the  Ordovician  areas 
while  in  others  lenticular  remnants  of  the  Ordovician  slate 
overlie  the  Lower  Cambrian  slate.  (See  Fig.  250.) 

Color. — The  Lower  Cambrian  slates  of  western  Vermont  are 
greenish  gray,  purplish  and  variegated.  These  colors  occur 
in  alternations.  In  the  main  the  horizon  seems  to  consist  of 
greenish  and  purplish  slates  varying  in  thickness  from  100  to 
200  feet  with  the  greenish  shades  predominating.  The  varie- 
gated or  mottled  overlying  slate  varies  from  40  to  50  feet  in 
thickness.  On  the  west  side  of  Lake  Bomoseen  nearly  100  feet 
of  purple  slate  is  exposed.  The  shade  of  green  is  not  con- 
stant even  in  the  same  quarry,  some  being  more  greenish, 


Fig.  251. — Slab  of  purplish  black  slate,  Castleton,  Vermont,  show- 
ing perfect  cleavage.  Photo,  by  C.  H.  Richardson. 

others  more  grayish.  There  is  also  a  difference  in  the  amount 
of  discoloration  produced  by  weathering  in  beds  in  the  same 
locality.  Some  quarries  produce  only  the  so-called  unfading 
green  and  others  only  the  sea  green.  These  differences  appear 
not  to  belong  to  strata  of  different  ages,  but  to  occur  at  dif- 
ferent points  in  strata  of  the  same  age.  (See  Fig.  251.) 

Lower  Cambrian. — The  Lower  Cambrian  rocks  consist  of  gray- 
wackes,  roofing  slates  with  beds  of  a  calcareous  quartzite  and 
a  limestone  breccia,  a  sandstone  with  black  shaly  patches, 
black  shale  and  slate,  ferruginous  quartzite  and  sandstone. 

Ordovician. — The  Ordovician  rocks  consist  of  shales,  slates, 
grits  and  small  quartzite  beds. 

Characteristics  of  Western  Vermont  Slates. 

Sea  Green  Slate. — This  slate  varies  from  a  light  gray  to    a 


288  BUILDING    STONES   AND    CLAYS 

greenish  gray  in  color.  In  some  beds  it  is  crossed  by  ribbons 
of  a  dark  gray  color.  The  texture  is  fine,  the  cleavage  surface 
smooth  with  a  somewhat  waxy  luster.  The  sawn  edge  shows 
a  little  pyrite.  It  is  feebly  magnetitic  and  effervesces  slightly 
with  cold  dilute  HC1.  It  is  sonorous  and  very  fissile.  On  long 
exposure  it  changes  to  a  brownish  gray  color.  As  the  beds  do 
not  discolor  uniformly  a  roof  covered  with  sea  green  slate 
from  different  beds  will  present  a  mottled  appearance.  The 
discoloration  is  due  to  oxidation  of  the  iron  content  of  the 
calcite  rhombs  to  limonite. 

Unfading  Green  Slate. — This  slate  is  greenish  gray  in  color, 
with  fine  texture  and  a  roughish,  lusterless  cleavage  surface. 
It  is  magnetitic,  but  does  not  effervesce  with  cold  dilute  HC1. 
It  is  sonorous.  This  slate  after  several  years  of  exposure  to 
the  corrosive  agents  of  the  atmosphere  evinces  no  perceptible 
change  unless  placed  beside  a  perfectly  fresh  slate  and  then  the 
difference  is  slight.  Acording  to  W.  F.  Hillebrand  the  per- 
manency of  color  is  due  to  the  practical  absence  of  rhombs 
and  plates  of  carbonate. 

Purple  Slate. — This  slate  is  a  dark  purplish  brown.  It  occurs 
interbedded  with  the  sea  green  and  unfading  green  slates.  Its 
texture  is  fine  and  cleavage  surface  smooth.  It  is  sonorous. 
The  carbonates  occur  in  less  abundance  in  this  slate  than  in 
the  sea  green  slate  but  it  bears  bright  red  dots  of  hematite 
ranging  in  diameter  from  0.001  to  0.003  mm. 

Variegated  Slate. — The  variegated  slate  is  of  greenish  gray 
and  purplish  colors  mixed.  It  is  of  fine  texture  with  smooth 
cleavage  and  sonorous.  The  variegated  slate  of  the  Eureka 
quarry  does  not  effervesce  with  cold  dilute  HC1. 

Red  Slate. — This  slate  is  of  reddish  brown  color  which  becomes 
brighter  upon  exposure.  Its  texture  is  fine,  and  its  cleavage 
surface  varies  from  slightly  roughish  to  speckled  with  minute 
protuberances.  It  is  magnetitic,  hematitic,  argillaceous,  sonorous 
and  sometimes  effervesces  with  cold  dilute  HC1.  Its  color  is 
due  to  the  abundance  of  hematite.  (See  Fig.  242.) 

Dove  Slate. — This  slate  is  of  light  gray  color,  fine  texture  and 
smooth  cleavage  surface.  It  contains  a  large  amount  of  mus- 
covite  (sericite)  and  is  sonorous. 

Mill-Stock  Slate. — In  the  northern  and  western  part  of  the 
green  slate  area  those  beds  which  have  a  less  perfect  cleavage 
are  used  as  mill  stock.  They  are  purple  or  green  in  color. 
The  purple  is  often  paler  than  the  purple  roofing  slate,  and  also- 
spotted  with  green.  The  green  mill  stock  is  sometimes 
brighter  than  the  unfading  green  roofing  slate. 


SHALE    AND    SLATE  289 

Slatc-Pcncil  Slate. — In  the  unfading  green  slate  areas  a  little 
to  the  east  of  Lake  Bomoseen  there  occurs  a  greenish  slate 
that  has  been  quarried  and  made  into  slate  pencils. 

In  Europe  slate  pencils  are  manufactured  by  utilizing  a 
secondary  cleavage  which  breaks  the  rock  up  into  squarish 
sticks  that  are  easily  rounded.  In  Vermont  tile-shaped  blocks 
of  slate  are  carved  out  first  on  one  side,  then  on  the  other,  by 
means  of  set  gauges,  and  thus  a  whole  series  of  semicylin- 
drical  pencils  which  readily  break  apart  into  roundish  pencils 
is  prepared  at  once. 

(4)  THE;  BENSON  BELT. — This  district  is  located  in  the  town  of 
Benson,  Rutland  County,  near  Lake  Champlain.  The  district 
comprises  an  area  of  10  or  12  square  miles  and  is  practically 
undeveloped.  The  entire  slate  belt  is  about  25  miles  in  length, 
with  strike  in  a  northeasterly  direction.  The  quarrying  of 
black  roofing  slates  in  the  belt  has  been  confined  to  the  town 
of  Benson.  These  quarries  were  in  operation  in  1895,  but  are 
now  abandoned.  This  slate  is  of  Ordovician  age. 

The  slate  is  bluish  black  in  color.  It  has  a  fine  texture,  a 
smooth  lustrous  cleavage  surface,  and  a  fair  degree  of  fissility. 
It  is  graphitic,  magnetitic,  effervesces  with  cold  dilute  HC1 
and  is  sonorous.  It  is  closely  related  in  both  composition  and 
quality  to  the  "soft  vein"  slates  of  Lehigh  and  Northampton 
Counties,  Pennsylvania. 

Virginia. — Commercial  slates  occur  in  Virginia  in  Amherst, 
Buckingham,  Fauquier  and  Fluvanna  Counties. 

Snowden,  Amherst  County. — The  Snowden  slate  deposit  is 
situated  on  the  southeast  side  of  the  axis  of  the  Blue  Ridge, 
north  of  the  cut  through  which  the  James  River  flows.  It  is 
also  about  18  miles  northwest  of  Lynchburg.  The  general 
strike  of  the  slate  formation  is  north  65  degrees  east.  About 
250  feet  of  slate  is  exposed  on  the  property  of  the  Virginia 
Slate  Mining  Company.  The  structure  is  that  of  a  flat-topped 
anticline. 

This  slate  is  of  dark  gray  color,  minutely  granular  texture, 
smooth  cleavage  surface,  and  very  little  luster.  It  bears  no 
visible  graphite,  pyrite  or  magnetite.  It  possesses  an  argilla- 
ceous odor  and  is  said  to  be  unfading.  It  does  not  effervesce 
with  cold  dilute  HC1  and  is  sonorous. 

Arvonia,  Buckingham  County. — The  quarries  near  Arvonia  are 
situated  on  both  sides  of  Hunts  Creek  and  a  little  to  the 
northeast  of  Arvonia.  The  "Gig  quarry"  of  the  J.  R.  Williams 
Slate  Company  measures  300  feet  along  the  cleavage,  200  feet 
across  it,  and  125  feet  in  depth.  The  bedding  planes  coincide 
19 


290  BUILDING    STONES   AND    CLAYS 

with  the  cleavage  planes.  The  strike  is  north  37°  east  and  the 
dip  is  86°  to  the  southeast. 

The  "Middle  quarry,"  which  is  owned  by  the  same  com- 
pany, measures  500  feet  along  the  cleavage,  350  feet  across  it 
and  in  places  350  feet  in  depth.  The  bedding  and  cleavage 
strike  is  north  33°  east  and  the  dip  is  85°  to  the  southeast. 

The  slate  of  the  Williams  quarries  is  of  very  dark  gray  color 
with  a  slightly  greenish  hue.  It  has  a  minutely  granular 
texture,  is  slightly  roughish  and  quite  lustrous.  It  bears  a 
little  graphite,  magnetite  and  pyrite.  It  is  sonorous  but  does, 
not  effervesce  with  cold  dilute  HCL 

The  Fontaine  quarry  of  A.  L.  Pitts  measures  300  feet  along 
the  cleavage,  200  feet  across  it,  and  100  feet  in  depth.  The 
bedding  and  cleavage  strike  is  north  34°  east  and  the  dip  is 
80°  to  the  southeast. 

This  slate  is  of  dark  gray  color  with  a  greenish  hue.  It  has 
a  granular  crystalline  texture  and  is  roughish,  on  its  cleavage 
surface.  It  bears  a  little  graphite,  magnetite  and  pyrite  and  is 
sonorous.  It  does  not  effervesce  with  cold  dilute  HCL 

Warrenton,  Fauquier  County. — There  are  several  slate  pros- 
pects in  the  neighborhood  of  White  Sulphur  Springs.  The 
cleavage  strike  varies  from  north  25°  east  and  west.  The  dip 
is  about  25°  to  the  west. 

The  slate  is  of  bluish  black  color  with  moderately  fine 
texture  and  cleavage  surface.  It  bears  graphite  and  pyrite  but 
no  magnetite.  It  is  argillaceous  and  sonorous  but  does  not 
effervesce  with  cold  dilute  HC1. 

Bremo,  Fluvanna  County. — The  Bremo  quarries  are  situated 
about  2  miles  northwest  of  Bremo  Bluffs.  The  strike  varies 
from  north  18°  east  to  north  23°  east  and  the  dip  is  nearly 
vertical. 

The  slate  is  of  dark  gray  color,  with  fine  and  lustrous 
cleavage  surface.  It  is  slightly  graphitic  and  pyritic  but  not 
magnetitic.  It  is  argillaceous,  sonorous  and  very  fissile.  It 
does  not  effervesce  with  cold  dilute  HCL 

According  to  E.  O.  Ulrich  the  Virginia  slates  are  of  Upper 
Devonian  age. 

West  Virginia. — The  slate  belt  of  West  Virginia  is  situated 
near  Martinsburg  in  Berkerley  County.  This  formation  is 
designated  in  the  Harpers  Ferry  folio  of  the  United  States 
Geological  Survey  as  Martinsburg  shale.  The  shale  is  esti- 
mated at  from  TOO  to  1,000  feet  in  thickness  and  is  of  Ordo- 
vician  age. 

The   old   quarries   of   the    Shenandoah    Slate    Company   are 


SHALE    AND    SLATE  291 

situated  about  3  miles  to  the  northeast  of  Martinsburg.  The 
quarry  is  100  feet  in  length,  TO  feet  in  breadth,  and  75  feet  in 
depth.  The  strike  of  the  bedding  planes  is  north  25°  east  and 
the  dip  15°  south,  and  65°  east.  The  cleavage  has  the  same 
strike  as  the  bedding  planes  and  dips  at  an  angle  of  75°  in  the 
same  direction. 

The  slate  is  of  black  color  with  a  slightly  brownish  hue.  The 
texture  is  fine,  the  cleavage  surface  roughish  and  lusterless. 
The  slate  is  carbonaceous,  magnetitic,  pyritic,  sonorous  and 
argillaceous  but  not  graphitic.  It  effervesces  with  col'd  dilute 
HC1. 

According  to  T.  N.  Dale  the  accessory  mineral  composition  of 
this  slate  in  descending  order  is  calcite,  muscovite,  quartz,  kaolin, 
pyrite,  carbonaceous  matter,  chlorite  and  magnetite.  It  is  a  clay 
slate  which  is  better  adapted  for  mill  stock  than  roofing  purposes. 

Some  2  miles  to  the  south  of  Martinsburg  there  is  another 
small  quarry,  30  by  20  feet.  The  bedding  strike  is  north  32° 
east  and  the  dip  60-65°  east.  The  cleavage  strike  is  north  23° 
east  and  the  dip  80°  east. 

About  one  mile  southeast  of  Beddington  there  is  a  slate 
which  bears  fragments  of  feldspar  and  rutile  needles.  Several 
other  small  quarries  are  located  in  the  Martinsburg  district. 
They  are  all  clay  slates  and  none  of  them  shows  a  complete 
seritization  of  the  matrix.  They  are  not  sufficiently  fissile, 
strong  and  elastic  to  successfully  compete  with  mica  slates 
for  roofing  purposes. 

FOREIGN   SLATES 

Canada. — Slates  of  excellent  quality,  smooth,  homogeneous, 
strong,  and  of  green-red,  purple  and  bluish  black  colors  abound  in 
the  Province  of  Quebec.  All  of  these  varieties  are  imported  and 
found  in  the  principal  slate  markets  of  the  United  States. 

Slate  of  good  quality  is  also  found  at  New  Canaan,  Nova 
Scotia. 

England. — The  Honister  quarries,  near  Keswick,  Cumber- 
land, furnish  a  dark  green,  compact  and  fine  grained  slate  in 
considerable  quantities.  The  basement  of  the  War  Memorial 
Building  in  the  City  of  York  is  an  example  of  the  value  of  this 
stone  in  structural  work.  The  stone  is  of  Ordovician  age. 

The  Elterwater  quarries,  Ambleside,  Westmoreland,  offer 
a  very  fine  grained  slate  of  green  color  and  Ordovician  age. 
The  War  Memorial  Building  at  Penrith  presents  an  example 
of  this  slate. 


292  BUILDING    STONES   AND    CLAYS 

France. — The  slates  of  the  Angers  district  are  strong, 
tough  and  of  bluish  gray  color.  They  have  been  used  in 
many  public  buildings  in  France  and  exported  somewhat 
from  the  port  of  Nantes.  These  slates  are  of  Ordovician 
age.  The  slates  in  Morbihan  are  also  of  Ordovician  age. 
They  are  strong,  elastic  and  of  pale  gray  color.  The  quarries 
are  open  cut  on  account  of  the  frequent  jointing  in  the 
slate  which  would  make  mining  unsafe. 

The  Cambrian  slates  of  the.  Ardennes  district  occupy  a 
comparatively  small  area.  They  are  micaceous,  chloritic  and 
contain  abundant  crystals  of  siderite.  They  frequently  con- 
tain white  spots  which  are  richer  in  silica  than  the  sur- 
rounding purple  portions  of  the  slate.  In  color  the  slates 
are  purple,  blue,  grayish  green  and  green.  The  green 
varieties  contain  crystals  of  magnetite.  These  small  crystals 
are  invisible  upon  the  cleavage  faces  of  the  slate  but  can 
be  observed  upon  the  fractured  ends  of  the  slate  blocks. 

Wales. — According  to  J.  Watson  the  Penrhyn  quarries  near 
Bangor  in  the  northern  part  of  Wales  produce  two  types  of 
fine  roofing  slates.  The  first  is  fine  grained  and  of  light  blue 
color.  The  second  is  fine  grained  and  of  dark  blue  color.  Both 
of  these  slates  are  of  Cambrian  age.  These  slates  are  very 
fissile  and  split  readily  into  extremely  thin  sheets.  The 
quarries  are  favorably  situated  both  for  working  and  ship- 
ment of  the  finished  products.  These  materials  have  found 
their  way  to  every  quarter  of  the  globe  and  doubtless  the 
slates  of  northern  Wales  have  been  more  extensively  used  for 
roofing  purposes  than  any  other  slates  of  the  \vorld. 

INDUSTRIAL  FACTS  ABOUT  SLATE 

Quarrying. — Before  opening  a  slate  quarry  the  commercial 
value  and  the  grade  of  fissility  of  the  slate  should  be  deter- 
mined by  scientific  and  practical  tests.  The  problems  to  be 
considered  concern  the  thickness  of  the  formation,  the 
weathered  top,  the  character  of  the  jointing,  the  presence  of 
faults,  shear  zone  and  dikes.  The  practical  question  of  drain- 
age, location  of  dumps,  availability  of  fuel,  and  transportation 
facilities  will  also  arise. 

In  quarrying  slates  ordinary  blasting  powder  has  long  been 
used.  The  experienced  workman  will  so  manipulate  his  blast 
as  to  free  large  blocks  from  their  bed  without  shattering  the 
slate.  Where  slate  quarries  are  traversed  by  veins  of  secondary 
quartz  much  good  slate  has  been  wasted  by  improper  manipu- 
lation of  blasts. 


SHALE    AND    SLATE  '  293 

Channelling  machines  are  now  often  used.  The  open  cut 
method  obtains  in  the  United  States,  both  in  the  opening  of 
a  quarry  and  in  its  subsequent  development.  The  recent  in- 
troduction of  the  method  of  tunnelling  in  the  slate  quarries 
of  Angers,  France,  is  a  step  in  advance  for  three  reasons. 
(1)  It  avoids  the  necessity  of  removing  the  overlying  soil  and 
weathered  slate.  (2)  It  protects  the  workmen  during  storms 
and  in  the  winter.  (3)  It  preserves  the  moisture  in  the  ex- 
posed slate.  Wherever  the  tunnelling  method  is  adopted  there 
should  be  a  frequent  inspection  of  the  walls  and  roof  to  detect 


Fig.  252. — Splitting  slate,  Pen  Argyl,  Pennsylvania.  Photo,  by 
J.  N.  Howell. 

and  mark  all  signs  of  rock  movement  in  order  that  accidents 
may  be  averted. 

Manufacture. — Roofing  slates  pass  through  three  operations 
in  the  process  of  manufacture.  These  are  blockmaking,  split- 
ting and  dressing.  In  some  instances  they  are  also  punched 
and  counter-sunk.  Formerly  these  operations  were  conducted 
by  hand,  but  modern  machinery  is  rapidly  displacing  hand 
work.  (See  Fig.  252.) 

The  slate  is  hoisted  from  the  quarry  in  blocks  which  average 
about  6  feet  by  3  feet  by  1.5  feet.  It  is  then  conveyed  to  a 
cabin  or  shanty,  where  it  is  treated  by  a  blockmaker,  a  splitter 


294 


BUILDING    STONES   AND    CLAYS 


and  a  dresser.  The  blockmaker,  with  a  chisel,  divides  the 
original  blocks  obtained  from  the  quarry  into  manageable 
slabs  about  2  feet  by  1.5  feet  by  2  inches  in  thickness.  In 
making  the  cut  across  the  grain  the  process  is  termed  sculping. 
A  V-shaped  notch  is  cut  in  one  end  of  the  block  and  trimmed 
out  with  a  smooth  gouge  to  a  groove  extending  across  the 
end  of  the  block.  The  splitting  chisel  is  held  with  edge  ver- 


Fig.    253. — Slate    splitting    machine    in    operation.      By    courtesy    of 
the   U.   S.   Geological   Survey. 

tical  to  this  notch  and  then  struck  with  a  hammer.  The  slab 
then  passes  to  the  splitter,  whose  splitting  chisel  is  about  12 
inches  long  and  with  an  edge  from  2  to  3  inches  broad.  This 
chisel  is  driven  with  a  maul  into  the  slate  along  the  cleavage 
planes,  and  then  worked  backward  and  for\vard  until  the  slate 
splits.  The  splitting  is  continued  until  the  slabs  are  reduced 
to  a  thickness  of  one-eighth  to  one-fourth  of  an  inch.  The 
slate  now  passes  to  the  dresser  or  trimmer,  who  formerly 


SHALE   AND    SLATE  295 

trimmed  all  slates  with  a  knife.  Hand  and  foot  power  dressing 
machines  are  now  largely  used.  The  design  is  a  long  knife 
set  vertically  and  hinged  at  one  end.  The  other  end  of  the  knife 
is  alternately  raised  or  lowered  by  hand  or  by  a  treadle.  (See 
Fig.  253.) 

Splitting  is  still  done  by  hand  labor,  as  mechanical  splitters 
have  rarely  given  good  satisfaction.  The  blocks  are  often 
given  at  least  one  sawed  edge  before  they  are  passed  on  to  the 
splitter.  This  is  done  on  a  sawing  table  with  a  vertical  saw 
such  as  is  used  in  the  preparation  of  mill  stock. 

Measurement. — Two  different  units  of  measurement  appear 
in  the  slate  trade.  The  square  is  used  in  all  American  markets 
and  the  mille  in  all  French  and  English  markets.  The  square 
is  the  number  of  slates  of  a  given  size  required  to  cover  100 
square  feet  of  roofing,  with  a  given  lap. 

E.  C.  Eckel  in  his  "Building  Stone  and  Clays"  gives  the  fol- 
lowing formula :  Let  b  equal  the  breadth  of  slates,  d  equal  the 
length  of  slates  and  1  equal  lap.  Then  the  number  of  slates  to 
the  square  will  equal  14,400  divided  by  one-half  bd-bl,  or  28,800 
divided  by  bd-bl.  This  formula  can  be  used  for  computing 
the  number  of  slates  to  the  square  for  any  given  size  and  lap. 
b,  d  and  1  are  in  inches. 

The  mille  is  1200  slates  of  any  given  size.  In  Europe  slates 
are  shipped  at  the  purchaser's  risk  and  60  slates  are  added  to 
cover  breakage.  The  actual  mille  therefore  becomes  1,260 
slates. 

If,  for  a  lap  of  3  inches,  slates  are  cut 

3x7  inches  one  square  will  require  2,400  slates 
4x7  inches  one  square  will  require  1,800  slates 
4x9  inches  one  square  will  require  1,200  slates 
8x9  inches  one  square  will  require  600  slates 
14  x  24  inches  one  square  wrill  require  98  slates 

Uses. — The  wide  range  of  color,  texture  and  composition  in 
slates  renders  them  capable  of  wide  industrial  application. 
Nearly  all  slates  possess  one  or  more  excellent  features,  few 
possess  many  such  features  and  none  possess  them  all.  The 
soft-vein  slate  of  Pennsylvania  is  well  suited  for  blackboards, 
slates,  slate  pencils,  billiard  tables,  mantels  and  urinals.  The 
red  roofing  slates  of  New  York  and  Vermont,  because  they 
increase  in  brightness  of  color  on  prolonged  exposure,  make 
excellent  roofing  material.  The  fadeless  bright  green  slates 
associated  with  the  red  slates  are  perhaps  equally  desirable 


296  BUILDING    STONES   AND    CLAYS 

for  roofing  purposes.  The  black  unfading  slates  of  the  Peach 
Bottom  district  of  Maryland  and  Pennsylvania,  of  Arvonia, 
Penlan  and  Esmont  in  Virginia,  and  of  Monson  and  Brown- 
ville  in  Maine,  are  all  good  roofing  slates.  The  almost  un- 
fading green  slates  of  Vermont  will  always  be  in  demand. 
The  sea  green  slates  of  Vermont  and  the  black  slates  of  Lehigh 
and  Northumberland  Counties,  Pennsylvania,  carry  a  content 
of  ferrous  carbonate.  Some  architects  are  reported  as  pre- 
ferring such  fading  slates  for  aesthetic  reasons. 

Slates  are  used  also  for  underpinnings,  floor  tiles,  risers  and 
treads  of  stairways  and  for  flagging  purposes.  Slate  is  some- 
times marbleized  for  mantels  and  fireplaces.  Any  kind  of 
stone  may  be  imitated  but  the  verd  antique  marble  of  Ver- 
mont and  the  variegated  marble  of  Tennessee  are  those  most 
frequently  seen  imitated. 

Mill  stock  is  used  for  electrical  purposes.  This  use  requires 
a  minimum  amount  of  magnetite. 

Slates  may  be  used  to  good  advantage  for  inexpensive 
tablets  and  gravestones.  There  are  many  places  where  thick 
slate  slabs  with  their  high  transverse  strength  may  be  used  to 
advantage  instead  of  concrete  beams.  Slate  has  also  been  sub- 
stituted as  veneers  for  laths. 

Slate  Waste. — The  percentage  of  waste  in  slate  quarrying 
and  manufacture  has  been  estimated  by  N.  Watrin  for  the 
Ardennes  region  as  varying  from  70  to  75  per  cent  of  the  total 
weight.  From  20  to  25  per  cent  is  lost  in  the  quarrying  and 
about  50  per  cent  in  splitting  the  slabs. 

G.  P.  Merrill  has  estimated  the  total  waste  in  the  Peach 
Bottom  district  as  88  per  cent.  The  waste  in  all  quarries  is 
large  and  the  substitution,  wherever  practicable,  of  mechanical 
cutting  machinery  for  blasting  is  probably  the  most  available 
method  for  effecting  this  reduction. 

In  several  localities  slate  waste  has  been  utilized  in  the 
betterment  of  roads.  The  growing  use  in  roofing  of  granu- 
lated slates  consumes  slate  with  imperfect  cleavage.  These 
slates  near  the  ridge  are  one-fourth  inch  in  thickness  and  at 
the  cornice  are  one  and  one-half  inches  in  thickness.  The 
Inlaid-Slate  Company  of  Bangor,  Pa.,  utilizes  slate  3  inches 
square  embedded  in  a  mixture  of  asphalt  with  a  high  melting 
point  and  a  backing  of  roofing  felt  for  covering  flat  roofs. 
Powdered  slate  is  used  as  a  filler  for  oilcloth  and  other  fabrics. 
The  waste  of  the  bright  red  slate  quarries  of  Granville,  New 
York,  is  used  for  roofing  and  bridge  paint.  It  is  mixed  with 
oil  and  white  lead. 


SRALE    AND    SLATE  297 

In  Norway  waste  slate  is  powdered  and  mixed  with  either 
solid  or  liquid  casein,  according  to  the  nature  of  the  slate.  The 
casein  may  be  pure  or  mixed  with  lime,  soda,  resins  or  acids, 
according  to  the  character  of  the  product  desired.  Coloring 
matter  is  often  introduced  to  produce  different  tints.  The 
material  when  plastic  is  placed  in  molds  and  subjected  to 
pressure.  The  product  is  then  air  dried.  The  resultant 
product  has  many  properties  identical  with  slate  but  is 
stronger  and  tougher. 

The  compressed  slate  can  be  sawed,  planed  and  polished. 
All  manner  of  fancy  designs  can  be  imprinted  on  the  plastic 
slate,  which  may  be  manufactured  into  blocks  of  uniform  size. 
The  material  is  designed  for  covering  walls,  either  internally 
or  externally,  in  the  place  of  ordinary  wall  paper  or  plaster. 
It  also  enhances  the  picturesqueness  of  slate  roofs.  Embossed 
mantlepieces  are  also  possible. 

Comparative  Tests. — The  transverse  strength  of  slates  is  of 
considerable  importance  and  should  always  be  known  before 
selecting  a  given  slate  for  building  purposes.  In  the  best 
slates  the  modulus  of  rupture  expressed  in  pounds  per  square 
inch  should  range  from  7,000  to  10,000.  M.  Merriman  has 
devised  a  method  of  determining  this  strength  and  gives  the 
results  as  follows : 

Lbs.  Per  Sq.  In. 

Green,  Vermont 6,410 

Albion  quarry,  Pen  Argyl,  Pa 7,150 

Green,  Rising  and  Nelson,  Vt 7,350 

Green,  Granville,  N.  Y 8,050 

Dark  gray,  Arvonia,  Va 9,040 

Gray,  Monson,  Me 9,130 

Red,  Granville,  N.  Y 9,220 

Dark  gray,  Chapman,  Pa 9,460 

Dark  gray,  Bangor,  Pa 9,810 

Dark  gray,  Arvonia,  Va 9,850 

Gray,  Brownville,  Me 9,880 

Peach  Bottom  district,  Penn.-Md 11,260 

Chemical  Analyses. — A  few  analyses  of  slates  are  appended 
here  as  a  matter  of  reference.  In  order  to  give  a  correct  idea 
of  the  composition  of  slates  these  analyses  should  not  be  par- 
tial but  complete.  The  strongest  and  best  slates  are  those 
with  the  highest  percentage  of  silicates  of  iron  and  alumina, 
but  these  slates  need  not  necessarily  be  the  lowest  in  their 
carbonates  of  lime  and  magnesia.  Chemical  analyses  should 


298  BUILDING    STONES   AND    CLAYS 

always  be  supplemented  with  a  microscopic  analysis,  tests  for 
transverse  strength,  elasticity,  porosity,   and  corrosibility. 

1.     Sample  of  slate  from  the  Old  Franklin  quarry,  Slating- 
ton,  Pa.     The  analysis  was  made  by  W.  F.  Hillebrand. 

Silica,   SiO2 - 56.38% 

Alumina,   A12O3 15.27 

Ferric  oxide,  Fe2O3,  approximate 1.67 

Ferrous  oxide,  FeO  3.23 

Magnesia,  MgO  2.84 

Lime,  CaO  4.23 

Soda,  Na2O 1.30 

Potassa,  ~K2O   ." 3.51 

Water  below  110  degrees  F.,  H20 77 

Water  above  110  degrees  F.,  H20 4.09 

Titanium  dioxide,  TiO2 78 

Zirconium  dioxide,  ZrO2 Trace 

Carbon   dioxide,   CO2 3.67 

Phosphorous  oxide,  P2O5  17 

Chromium  oxide,   Cr2O:, Trace 

Manganous  oxide,  MnO - 09 

Baryta,  BaO  08 

Strontia,   SrO   Trace 

Lithia,  Li2O  Trace 

Pyrite,  FeS2  including  0.92  sulphur 1.72 

Carbon  or  carbonaceous  matter,  C...  .59 


2.     Samples  of  roofing  slate  from  Maryville,  Tenn.    Analysis 
made  by  Gilbert  McCulloch  of  the  University  of  Tennessee. 

Silica,   SiO,   .  58.45 

Alumina,  A1,O3   21.88 

Iron  oxide,  Fe2O.,  6.04 

Lime,  CaO 1.86 

Magnesia,  MgO  46 

Potassa,  K2O 1.60 

Soda,  Na26  2.34 

Sulphur  trioxide,  SO3  65 

Water,   H0O   .  ..  6.66 


99.94 


3.  Sample  of  purple  slate  from  Utah.  Analysis  by  W.  T. 
Schaller  in  the  laboratory  of  the  United  States  Geological 
Survey. 


SHALE    AND    SLATE  299 

Silica,  SiO2  54.05 

Alumina,  A12O3   20.95 

Iron  oxides,  FeO,  Fe2O3 28 

Lime,   CaO   22 

Magnesia,  MgO  9.12 

Carbon  dioxide,  CO,  and  water,  H2O  3.90 


88.52 

4.     Sample  of  sea  green  slate  from  West  Pawlet,  Vermont. 
Analysis  was  made  by  W.  F.  Hillebrand. 

Silica,  SiO2  62.76 

Rutile,  titanium  dioxide,  TiO2  71 

Alumina,  A12O3   19.12 

Ferric  oxides,  Fe,O3  81 

Ferrous  oxide,  FeO  4.71 

Manganous  oxide,  MnO  10 

Nickelous  and  cobaltous  oxide,  NiO,  CoO Trace 

Lime,   CaO 63 

Baryta,  BaO 04 

Magnesia,  MgO 2.38 

Potassa,  K,O .:. 3.52 

Soda,  Na2O  1.39 

Lithia,    Li2O Strong 

Water  below  110  degrees  F.,  H20 23 

Water  above  110  degrees  F.,  H~O -  2.98 

Phosphorous  oxide,  P2O5  07 

Carbon  dioxide,  CO,  .." 40 

Pyrite,   FeS,   " 22 

Sulphur  trioxide,  SO3  Trace 

Carbon,  C  ..  ...None 


100.07 

5.     Sample  of  red  slate  from  Hampton,  New  York.  Analysis 
made  by  W.  F.  Hillebrand. 

Silica,  SiO2  67.61 

Titanium  dioxide,  TiO2  56 

Alumina,  A1,O3   " 13.20 

Ferric  oxide,"  Fe2O3  5.36 

Ferrous  oxide,  FeO  1.20 

Manganous  oxide,  MnO  10 

Nickelous  oxide,  NiO Trace 

Cobaltous  oxide,  CoO Trace 

Lime,   CaO   11 

Baryta,  BaO  , 04 

Magnesia,  MgO 3.20 


300 


BUILDING    STONES   AND    CLAYS 


Potassa,   K0O   ,. 4.45 

Soda,  Na,6  ..., 67 

Lithia,  Li2O  - .-Trace 

Water  below  110  degrees  F.,  H2O-.  .45 

Water  above  110  degrees  F.,  H,O ..  2.97 

Phosphorous  oxide,   P2Og  - .05 

Carbon  dioxide,  CO2 - .....None 

Pyrite,    FeS2   -  .03 

Carbon,  C  ..  ...None 


100.00 
Total  sulphur,  S  ..  .016 

6.     Sample   of  black   roofing  slate   from   Benson,   Vermont. 
Analysis  was  made  by  W.  F.  Hillebrand. 

Silica,   SiQ,   .  ...59.70 

Titanium  dioxide,  rutile,  TiO2  ..  .79 

Alumina,  A12O3 16.98 

Ferric  oxide,  Fe2O3 52 

Ferrous  oxide,  FeO  4.88 

Manganous  oxide,  MnO  - 16 

Nickelous  oxide,  NiO Trace 

Cobaltous  oxide,  CoO Trace 

Lime,  CaO  1.27 

Baryta,  BaO  .08 

Magnesia,  MgO 3.23 

Potassa,   K9O   .  3.77 

Soda,  Na2O  ..  1.35 

Lithia  Li2O  Strong  trace 

Water  below  110  degrees  F.,  H2O... .30 

Water  above  1.10  degrees  F.,  H2O 3.82 

Phosphorous  oxide,  P2O5 .16 

Carbon  dioxide,  CO2 1.40 

Pyrite,   FeS2   .  -  1.18 

Sulphur  trioxide,   SO8   - Trace 

Carbon,   C .46 


Total  sulphur,  S 


100.05 
.63 


SHALE    AND    SLATE  301 

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Barnum,  G.    Slate  Mining  versus  Quarrying ;  Stone,  Vol.  28,  pp. 

219-227,  1907. 
Bayley,  W.  S.     Slate  from  Monson,  Piscataquis  County,  Maine ; 

U.  S.  Geol.  Survey  Bull.  150,  1898. 
Brunner,  H.    Valuation  of  Roofing  Slates ;  Soc.  Chem.  Ind.  Jour., 

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Survey  Bull.,  586,  1914. 
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1887. 
Eckel,  E.  C.    Building  Stones  and  Clays ;  John  Wiley  and  Sons, 

1912. 
Eckel,  E.  C.    The  Slate  Deposits  of  California  and  Utah;  U.  S. 

Geol.  Survey  Bull,  225,  1903. 
Ferguson,  E.  G.  W.    Peach  Bottom  Slate  Deposits,  Pennsylvania ; 

Min.  World,  Vol.  33,  pp.  183-184,  1910. 
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1906. 
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Nat.  Hist,  and  Geol.  of  Maine,  pp.  316-319,  1861. 
Howe,  J.  A.     The  Geology  of  Building  Stones ;  London,  1910. 
Hull,  E.  A.     A  Treatise  on  Building  and   Ornamental   Stones, 

London,  1872. 
Leighton,  H.     Slate   (Industry)    in  New  York  in   1909;  N.  Y. 

State  Museum  Bull.  142,  1910. 
Merrill,  G.  P.     Stones  for  Building  and  Decoration ;  New  York, 

1908. 
Nevins,  J.  N.     Roofing  Slate  Quarries  of  Washington  County, 

N.  Y. ;  New  York  State  Museum  53d.  Ann.  Rept.  for  1899, 

Albany,  1912. 


302  BUILDING    STONES   AND    CLAYS 

Perkins,  G.  H.     Report  of  the  State  Geologist  on  the  Mineral 

Industries  of  Vermont,  1900. 

Purdue,  A.  H.    The  Slates  of  Arkansas  ;  Geol.  Survey  Ark.,  1909. 
Richardson,  C.  H.     The  Terranes  of  Orange  County,  Vermont; 

Ann,  Rept.  State  Geologist,  1902. 
Ries,  H.     Building  Stones  and  Clay  Products ;  A.  Handbook  for 

Architects.     New  York,  1912. 
Shaler,    N.    S.      Slates,    Description    of    Quarries    and    Quarry 

Regions;  10th.  Census  U.  S.  Vol.  10,  Part  2,  1880. 
Smith,  T.  C.     Slate  Quarrying  in  Wales,  1860.     Also  two  later 

Editions. 

Watson,  J.    Building  Stones  ;  Cambridge,  1911. 
Watson,  T.  L.     Slate  in  Virginia ;  Virginia  Geol.   Survey  Bull. 

6,  1911. 
Whedon,  M.  D.    New  York- Vermont  Slate  Belt ;  Stone,  Vol.  28, 

pp.  214-218,  New  York,  1907. 


CHAPTER  VII 

SERPENTINE  AND  STEATITE 

In  the  minds  of  many  scientists  the  correct  position  of  this 
chapter  would  fall  at  the  close  of  the  discussion  of  the  building 
stones  of  igneous  origin.  The  author  of  this  work  has  chosen 
to  place  the  discussion  of  serpentine  and  steatite  at  the  close 
of  the  sedimentaries  for  two  reasons:  (1)  Strictly  speaking 
these  two  rocks  are  not  directly  igneous  in  origin.  (2)  They 
are  of  minor  commercial  significance  as  building  materials. 

These  two  minerals  or  rock  masses  have  many  points  in 
common,  although  their  uses  are  widely  different.  In  com- 
position they  are  hydrous  silicates  of  magnesium.  In  origin 
they  are  alteration  products  of  igneous  rocks  or  minerals. 
Their  similarities  will  be  more  fully  brought  out  under  the  re- 
spective captions  of  serpentine  and  steatite. 

SERPENTINE 

Serpentine,  Ophicalcite  and  Ophimagnesite. — The  name  ser- 
pentine is  derived  from  the  Latin  word  serpens,  a  serpent,  in 
allusion  to  the  snake-green  color  of  the  mineral  or  mottled 
appearance  of  the  rock  masses.  It  is  applied  not  only  to  the 
mineral  itself  but  also  to  the  rock  masses  consisting  essentially 
of  the  mineral  serpentine. 

Serpentine  is  a  hydrous  silicate  of  magnesium  with  formula 
3MgO,  2SiO2,  2H2O.  If  pure  its  percentage  composition 
would  be  Silica  44.1  per  cent.  Magnesia  43.0  per  cent.  Water 
12.9  per  cent.  Precious  serpentine  has  a  rich  oil-green  color, 
of  pale  or  dark  shades,  and  translucent  even  in  slabs  of  con- 
siderable thickness.  The  common  serpentine  usually  pos- 
sesses the  darker  shades  of  color  and  is  subtranslucent.  As  a 
rock  mass  it  occurs  frequently  mixed  with  dolomite,  magnesite 
and  calcite.  It  is  sometimes  mottled  with  red  and  then  it 
presents  the  appearance  of  a  red  porphyry. 

Ophicalcite  is  the  name  applied  to  the  spotted  green  and 
white  varieties  often  appearing  as  crystalline  marbles. 
It  consists  of  a  mixture  of  serpentine  with  calcite  or  dolomite, 
usually  of  sedimentary  origin.  Ophimagnesite  is  a  name  used 
for  the  first  time  by  E.  C.  Eckel  in  his  ''Building  Stones  and 

303 


304  BUILDING    STONES   AND    CLAYS 

Clays"  for  a  rock  containing  crystalline  magnesite  with  dis- 
seminated serpentine.  The  term  verd  antique  is  not  applied 
to  the  marble  of  any  particular  locality,  but  to  all  marbles 
containing  disseminated  seams,  streaks,  or  masses  of  the 
mineral  serpentine. 

Origin. — Serpentine  seldom  if  ever  occurs  as  an  original  de- 
posit. It  usually  is  derived  from  the  ultra-basic  rocks  rich  in 
olivine,  like  peridotite.  The  products  of  the  alterations  of 
olivine,  are  serpentine,  magnesite  and  sometimes  magnetite. 
The  pyroxene  diopside  may  be  metamorphosed  into  serpen- 
tine, calcite  and  quartz.  In  fact,  serpentine  may  be  derived 
from  any  silicate  rich  in  magnesia,  such  as  olivine,  pyroxene, 
amphibole,  garnet  and  chondrodite. 

In  the  case  of  the  ophicalcites  and  some  serpentine  deposits 
they  appear  to  have  been  derived  from  an  impure  limestone 
rich  in  silica  which  was  metamorphosed  into  a  siliceous 
marble.  The  impurities  present  in  the  original  sedimentary, 
with  possibly  some  additional  matter  from  other  sources,  gave 
rise  to  crystals  of  pyroxene,  amphibole  and  other  silicates. 
These  silicates  rich  in  magnesia  were  subsequently  altered  to 
serpentine. 

Characteristics. — Serpentine  is  susceptible  of  a  most  beauti- 
ful polish  when  it  does  not  contain  disseminated  magnetite, 
chromite  and  pyrite.  The  presence  of  these  secondary  min- 
erals leads  in  time  to  a  discoloration  due  to  the  oxidation  and 
hydration  of  the  iron  content.  The  veins  of  talc,  dolomite  and 
magnesite  with  which  serpentine  is  often  traversed  mark  lines 
of  weakness  in  the  stone,  for  each  represents  a  filled  fracture. 
It  is  therefore  impossible  to  obtain  large  blocks  that  will  with- 
stand high  pressure.  Most  serpentine  quarries  are  badly 
jointed  and  only  small  blocks  can  be  obtained.  The  stone 
furthermore  does  not  weather  uniformly  and  is  in  general  un- 
suited  for  exterior  work.  Some  of  the  structures  erected  with 
serpentine  from  Pennsylvania  evidence  this  variation. 

AMERICAN  SERPENTINES 

California. — Serpentine  forms  extensive  rock  masses  in  the 
Coast  Mountains  of  California.  It  occurs  also  in  numerous 
small  areas  in  the  Sierras.  Amador,  Los  Angeles  and  San 
Bernadino  Counties  have  been  the  chief  producers.  The  colors 
shade  from  a  yellowish  green  to  a  very  dark  olive  green.  In 
most  of  the  quarries  it  lacks  a  sufficient  brightness  of  color  to 
render  it  a  desirable  ornamental  stone.  According  to  L.  E. 


SERPENTINE   AND    STEATITE 


305 


Anbury  the  quarries  in  San  Bernadino  County  furnish  as 
handsome  stone  as  any  in  the  United  States.  (See  Fig.  254; 
also  Fig.  136.) 

Connecticut. — According  to  C.  U.  Shepard  two  quarries  in 
this  state  were  opened  in  the  early  part  of  the  nineteenth 
century  and  subsequently  abandoned.  The  working  of  the 
quarries  was  attended  with  heavy  expense  owing  to  the  diffi- 
culty of  obtaining  blocks  that  were  perfectly  sound,  of  large 
dimensions,  and  to  the  labor  required  in  sawing  and  polishing 
the  marble.  The  Milford  quarries  can  furnish  handsome  verd 
antique  marble,  while  the  New  Haven  quarries  can  produce  a 
dove  colored  marble  clouded  with  greenish  yellow  serpentine. 

Georgia. — A  massive  verd  antique  marble  is  quarried  in  this 


Fig.  254. — Polished  slab  of  serpentine,  Los  Angeles  County,  Cali- 
fornia. Photo,  by  C.  H.  Richardson. 

state  near  Holly  Springs,  Cherokee  County.  It  is  beautifully 
veined  and  well  adapted  to  interior  work. 

Maine. — The  best  known  serpentine  quarries  in  Maine  are 
situated  on  the  northern  end  of  Deer  Isle,  in  Penobscot  Bay. 
They  are  in  close  proximity  to  a  good  shipping  wharf  and 
larger  blocks  of  serpentine  can  here  be  obtained  than  in  most 
other  quarries.  The  stone  is  of  a  dark  green  color,  sometimes 
nearly  black  and  somewhat  somber.  It  is  often  veined  with 
amianthus  and  diallage. 

Maryland. — Near  Broad  Creek  in  Harford  County  there  are 
two  beds  of  serpentine  which  have  been  quarried  from  time  to 
time  for  decorative  material.  The  upper  bed  is  about  500  feet 
in  thickness  and  of  green  color.  The  lower  bed  shades  in  color 

20 


306  BUILDING    STONES   AND    CLAYS 

from  a  pale  leek  green  to  a  deep  blackish  green.  It  is  some- 
what translucent,  tough  and  harder  than  common  marble. 

Massachusetts. — There  are  many  occurrences  of  serpentine 
in  the  Hoosic  Mountains.  W.  O.  Crosby  has  suggested  that 
the  quantity  is  adequate  for  the  entire  world,  yet  the  quarries 
have  never  been  extensively  operated.  Precious  serpentine  can 
be  obtained  in  Middlefield  and  Pelham.  Common  serpentine 
for  ornamental  architecture  occurs  in  the  towns  of  Blanford, 
Middlefield,  Newbury,  Lynnfield  and  Zoar. 

New  Jersey. — Serpentine  deposits  occur  in  this  state  in  the 
vicinity  of  Phillipsburg.  They  have  been  quarried  to  some 
extent  for  decorative  interior  work.  The  polished  slabs  are 
of  exceptional  beauty  but  blocks  of  only  small  dimensions 
appear  to  have  been  obtained. 

New  York. — Serpentine  occurs  on  the  west  side  of  Lake 
Champlain  in  the  vicinity  of  Moriah  and  Port  Henry  in 
numerous  outcrops  from  which  sound  blocks  of  considerable 
size  can  be  obtained.  Too  much  resistance  to  compression  must 
not  be  expected  of  these  blocks.  It  receives  a  good  polish  and 
is  better  suited  for  decorative  work  than  structural.  This 
serpentine  marble  consists  mainly  of  serpentine,  dolomite, 
calcite  and  phlogopite. 

North  Carolina. — According  to  G.  P.  Merrill  massive  va- 
rieties of  serpentine  occur  in  many  localities  within  this  state. 
Good  serpentine  can  be  obtained  near  Patterson,  Caldwell 
County.  It  is  of  a  dark  greenish  black  color,  traversed  by  fine 
veins  of  yellowish  green  and  silky  chrysotile.  This  stone  is 
susceptible  of  a  good  polish.  Dark  green  serpentine  has  also 
been  seen  by  the  author  near  Asheville  in  Buncombe  County. 

Pennsylvania. — The  best  known  serpentine  in  Pennsyl- 
vania is  quarried  near  Easton.  The  small  blocks  obtainable 
are  susceptible  of  a  fine  polish.  The  decorative  effect  of  this 
stone  can  be  seen  in  the  interior  of  the  Episcopal  Cathedral 
of  St.  John  the  Divine  in  New  York  City. 

Serpentine  deposits  are  also  abundant  in  the  southeastern 
part  of  the  state.  A  belt  of  serpentine  nine  miles  in  length  is 
known  to  occur  in  Chester  County.  Quarries  have  been 
worked  near  West  Chester  and  the  product  used  for  building 
purposes.  It  can  be  seen  in  some  of  the  buildings  of  the  Uni- 
versity of  Pennsylvania,  in  some  of  the  churches  of  Phila- 
delphia, in  the  Academy  of  Sciences,  Philadelphia,  and  in  the 
Monroe  Avenue  M.  E.  Church  in  Rochester.  The  church  in 
Rochester  is  trimmed  with  a  Triassic  brownstone. 

Vermont. — The   serpentine   belt   of   Vermont   extends   in   a 


SERPENTINE   AND    STEATITE 


307 


somewhat  northeasterly  direction  across  the  entire  state.  The 
old  quarries  in  Cavendish,  which  were  opened  about  1835  to 
obtain  a  structural  stone  of  great  beauty,  were  soon  aban- 
doned. Distance  from  the  railroad  together  with  the  cost  of 
quarrying,  dressing  and  polishing  the  stone  made  it  too  ex- 
pensive to  compete  successfully  with  the  well  known  marbles 
of  western  Vermont.  This  stone  is  of  varying  shades  of  green 
and  receives  a  fine  polish. 

The  best  known  American  serpentine  and  in  the  author's 


Fig.  255. — New  quarry  of  verd  antique  marble,  Roxbury,  Vermont. 
Photo,  by  C.  H.  Richardson. 

judgment  the  most  beautiful  is  quarried  at  Roxbury  in  Wash- 
ington County.  The  old  quarries  are  situated  within  100  rods 
of  the  Roxbury  station  on  the  Central  Vermont  railroad. 
Recent  quarries  have  been  opened  up  a  little  to  the  northeast 
of  the  old  quarries.  (See  Figs.  255  and  256.) 

The  origin  of  this  serpentine  is  through  the  alterations  of  a 
peridotite  dike  which  was  introduced  into  Cambrian  sediments 
in  pre-Ordovician  time.  About  one  mile  east  of  the  village  of 
North  Troy,  Vermont,  a  dike  of  diabase  cuts  the  steatite  out- 


308 


BUILDING    STONES   AND    CLAYS 


Fig.  256. — Rough  block  of  vcrd  antique  marble,  Roxbury,  Vermont, 
showing  work  of  channelling  machine.     Photo,  by  C.  H.  Richardson. 


Fig.    257. — Diabase    dike    cutting    steatite,    North    Troy,    Vermont. 
Photo,  by  C.  H.  Richardson. 


SERPENTINE   AND   STEATITE  309 

crop.  The  zone  of  metamorphism  at  the  contact  of  the  in- 
trusives  proves  them  not  contemporaneous.  This  peridotite  is 
exceedingly  common  in  its  more  northerly  extension  into 
Canada  where  it  cuts  terranes  considered  to  be  Ordovician, 
but  nowhere  in  Vermont  does  it  cut  strata  of  Ordovician  age. 
Pebbles  of  serpentine  have  been  found  in  the  Irasburg 
conglomerate  which  forms  the  basal  member  of  the  Ordovician 
series  in  Vermont,  therefore  the  peridotite  belt  in  northern 
Vermont  is  of  pre-Ordovician  age.  (See  Fig.  257.) 

The  serpentine  is  somewhat  fibrous  and  radial  in  texture 
with  veinlets  of  dolomite  and  talc.  The  unpolished  stone  is 
of  a  dark  purplish  or  greenish  color  traversed  with  many  veins 
of  white  dolomite.  The  polished  stone  is  of  dark  greenish 
black  color,  almost  black,  and  decorated  with  veins  of  white 
dolomite  and  light  green  talc.  These  veins  and  veinlets  are 
often  sheared  and  faulted,  which  indicates  that  the  stone  has 
been  subjected  to  powerful  compression  since  its  alteration  to 
serpentine. 

The  belt  of  serpentine  is  known  commercially  as  a  verd 
antique  marble.  The  high  polish  which  it  receives,  together 
with  the  striking  contrasts  in  shades  and  colors,  and  the 
faulted  and  sheared  veins,  renders  this  serpentine  a  very  at- 
tractive ornamental  stone  for  interior  work.  Too  much  must 
not  be  expected  of  it  for  constructional  purposes. 

In  Orleans  County  the  serpentine  belt  is  practically  con- 
tinuous across  the  entire  county.  In  the  more  northern 
portion  two  belts  of  serpentine  appear  which  flank  either  side 
of  the  Missisquoi  River.  The  largest  single  mass  is  on  the 
eastern  side  of  Belvidere  Mountain  in  Lowell  and  Eden,  where 
considerable  quantities  of  chrysotile  asbestos  have  been  mined 
and  marketed.  (See  Fig.  258.) 

Washington.— Three  varieties  of  serpentine  marbles  are 
quarried  in  Stevens  County,  Washington.  They  are  commer- 
cially known  as  Athenian  Green,  Landscape  Green  and  Royal 
Washington.  These  serpentines,  like  the  eastern  representa- 
tives, are  best  suited  for  decorative  interior  work. 

FOREIGN  SERPENTINES 

Canada. — All  of  the  varieties  of  serpentine  obtained  in  north- 
ern Vermont  may  be  duplicated  in  the  Province  of  Quebec. 
The  author  has  traversed  this  belt  in  its  northeasterly  exten- 
sion into  Canada  for  more  than  100  miles,  and  its  character- 
istics are  essentially  the  same  as  those  in  Vermont. 

England. — The   serpentine   deposits  of  Cornwall,   England, 


310 


BUILDING    STONES   AND    CLAYS 


fall  amongst  the  best  known  and  most  beautiful  serpentine 
marbles  of  the  world.  They  are  prevailingly  of  a  dark  olive 
green  color,  veined,  streaked  and  blotched  \vith  minerals  of 
greenish  white,  chocolate  brown  and  blood  red  hues. 

Ireland. — The  best  known  Irish  serpentine  is  called  Conne- 
mara  marble.  It  is  obtained  in  the  County  of  Galway  and  has 
been  imported  as  a  decorative  stone  to  some  extent  into  the 
United  States.  The  stone  is  of  light  to  dark  green  color, 
mottled,  streaked  and  variegated. 


Fig.  258. — Massive  serpentine  traversed  by  veins  of  fibrous  serpen- 
tine, chrysotile,  northeast  side  of  Belvidere  Mountain,  Lowell,  Ver- 
mont. Photo,  by  C.  H.  Richardson. 

Italy. — The  ophicalcites  of  Italy  are  well  known  decorative 
stones.  The  Verde  di  Pegli  is  a  breccia  consisting  of  deep 
green  fragments  of  serpentine  cemented  together  with  light 
green  calcite.  The  Verde  di  Genova  stone  from  the  quarries 
at  Pietra  Lavezzara  is  also  a  breccia  which  consists  of  green, 
greenish  black  and  brownish  serpentine  cemented  with  white 
or  greenish  white  calcite.  It  has  been  quarried  for  many 
centuries  and  the  product  shipped  largely  to  France.  The 
Verde  di  Levante  is  a  breccia  containing  fragments  of  serpen- 
tine of  a  violet  or  wine  red  color.  The  Verde  di  Prato  is  ob- 
tained from  the  serpentine  quarries  in  Tuscany.  It  is  of  deep 


SERPENTINE   AND    STEATITE 


311 


green  color  and  contains  crystals  or  nodules  of  diallage.  The 
network  of  fine  lines  or  veinlets  traversing  this  stone  gives  it 
the  appearance  of  a  breccia.  The  Nero  Antica  di  Prato,  which 
was  extensively  used  for  monuments  by  the  ancients,  is  of 
dark  green  color. 

INDUSTRIAL  FACTS  ABOUT  SERPENTINE 

Uses. — Serpentine  has  been  used  in  many  instances  in  the 
place  of  marble  for  structural  purposes.  The  dressed  stone 
does  not  weather  uniformly  for  the  white  and  yellowish  veins 
lose  their  luster  and  crumble.  The  entire  face  of  a  building 


Fig.  259. — Polished  slab  of  verd  antique  marble,  Maryland, 
by  C.  H.  Richardson. 


Photo. 


may  therefore  become  as  unsightly  as  it  once  was  beautiful. 
Its  resistance  to  compression  is  too  low  for  the  more  massive 
forms  of  architecture.  It  can  be  used  to  a  good  advantage  in 
columns  where  only  a  moderate  pressure  is  demanded.  It  has 
been  used  from  time  immemorial  for  monumental  work  in 
France  and  Italy.  In  later  years  it  has  been  used  somewhat 
for  that  purpose  in  America.  It  is  sufficiently  soft  to  be 
turned  and  polished  on  a  lathe.  Its  beautiful  colors  when 
polished  have  made  it  a  favorite  with  all  civilized  nations  for 
decorative  interior  work  and  for  small  articles  of  ornamenta- 
tion. (See  Fig.  259.) 

Ornamental  fronts,  pulpits,   small  shafts,  pillars,  pilasters, 


312  BUILDING   STONES   AND    CLAYS 

vases,  tazzas,  choir  steps,  ambulatories  and  inlaid  work  utilize 
serpentine.  The  finely  fibrous  variety  known  as  chrysotile  is 
now  being  manufactured  into  fireproof  lumber  wrhich  can  be 
planed,  sawed  and  finished  like  ordinary  lumber,  and  yet 
possesses  all  the  advantages  of  fireproof  material. 

Compression  Tests. — The  resistance  to  compression  of  some 
well  known  serpentines  is  here  given  as  a  matter  of  reference. 

Lbs.  Per  Sq.  In. 

Gillespie  County,  Texas 8,950 

Washington,  Milan,  dark 9,520 

California,  Auburn  11,590 

Germany  ...11,950 

Washington,  Milan,  light  yellow 13,530 

Washington,  Chewelah  17,310 

Washington,  Valley,  green 18,305 

Washington,  Valley,   black 29,750 

Chemical  Analyses. — A  few  analyses  are  also  appended  as  a 
matter  of  reference  to  show  the  general  chemical  composition 
of  serpentines. 

1.  This  sample  is  from  Valley,  Stevens  County,  Washing- 
ton. The  analysis  was  made  by  R.  W.  Thatcher. 

Silica,  SiO2  38.47% 

Alumina,  A12O3 0.16 

Ferric  oxide,  Fe2O3 2.04 

Ferrous  oxide,  FeO Trace 

Magnesia,    MgO 39.86 

Carbon  dioxide,  CO2 4.84 

Water,  H2O 14.63 


100.00 

2.  This  sample  is  also  from  Valley,  Washington,  from  the 
quarries  of  the  United  States  Marble  Company.  The  analysis 
was  made  by  George  Steiger.  The  large  decrease  in  silica  and 
increase  in  magnesia  and  water  is  notable. 

Silica,  SiO2 13.08 

Alumina,  A12O3 1.63 

Ferric  oxide,"  Fe2O3  1.25 

Ferrous  oxide,  FeO  0.19 

Lime,  CaO 0.33 

Magnesia,    MgO 56.44 

Carbon  dioxide,  CO2   2.03 

Water,  H2O 24.79 

99.74 


SERPENTINE   AND   STEATITE  313 

3.     An  old  analysis  of  the  verd  antique  marble  of  Roxbury, 
Vermont,  gives  the  following : 

Silica,  SiO2  42.60 

Magnesia,    MgO   35.50 

Chromic    and    ferrous    oxides,    Cr2O3, 

FeO  8.30 

Calcium  carbonate,  CaCO3  0.60 

Water,  H2O  13.00 


100.00 

4.  J.  Watson  in  his  book  entitled  "Building  Stones"  gives 
the  following  analysis  of  a  sample  of  serpentine  diabase  from 
the  Polyfant  quarries  near  Launceston,  Cornwall,  England : 

Silica,  SiO2  36.90 

Alumina,  A12O3  11.80 

Ferrijc  oxide,  Fe2O3  12.00 

Ferrous  oxide,  FeO  3.56 

Magnesia,    MgO   15.03 

Lime,  CaO  2,80 

Potash,    K2O    3.64 

Soda,  Na2O  Trace 

Water,  H2O  13.16 


98.89 
REFERENCES 

No  attempt  is  made  to  give  a  complete  bibliography  but  simply 
to  add  a  few  references  to  some  works  bearing  on  the  origin  and 
occurrences  of  serpentine. 

Aubury,  L.  E.  Structural  and  Industrial  Materials  of  Cali- 
fornia;  1906. 

Dresser,  J.  A.  Mineral  Deposits  of  the  Serpentine  Belt  of 
Southern  Quebec ;  Ann,  Rept.  Canadian  Geol.  Survey,  1909. 

Eckel,  E.  C.  Building  Stones  and  Clays.  John  Wiley  and 
Sons,  1912. 

Jacobs,  E.  E.  The  Talc  and  Verd  Antique  Deposits  of  Ver- 
mont; Ann  Rept.  State  Geol.,  1916. 

Jonas,  A.  J.  Serpentine  in  the  Vicinity  of  Philadelphia ; 
American  Geologist,  Vol.  36,  pp.  296-304,  1905. 

Hull,  E.  Building  and  Ornamental  Stones ;  Macmillan  and 
Company,  1872. 

Lyon,  D.  A.  Serpentine  Marbles  of  Washington.  Mines 
and  Minerals,  Vol.  21,  1901. 

Masters,  W.  F.  The  Serpentine  Belt  of  Lamoille  and 
Orleans  Counties,  Vermont ;  Ann.  Rept.,  State  Geologist,  1904. 


314:  BUILDING    STONES   AND    CLAYS 

Mathews,  E.  B.  Character  and  Distribution  of  Maryland 
Building  Stones ;  1898. 

Merrill,  G.  P.  Stones  for  Building  and  Decoration.  John 
Wiley  and  Sons.  Second  Edition. 

Ries,  H.  Building  Stones  and  Clay  Products;  John  Wiley 
and  Son.  1912. 

Richardson,  C.  H.  Asbestos  in  Vermont;  Ann.  Rept.  State 
Geologist,  1910. 

Richardson;  C.  H.  Asbestos  Deposits  of  the  New  England 
States;  Ann.  Rept.  Can.  Inst.  Min.  Engineers,  1910. 

Shedd,  S.  The  Building  and  Ornamental  Stones  of  Wash- 
ington ;  Ann.  Rept.  Washington  Geol.  Sur.,  1902.  Vol.  2, 
pp.  1-163. 

Wigglesworth,  E.  The  Serpentine  of  Vermont.  Proc. 
Boston  Soc.  Nat.  Hist.,  1915. 

STEATITE 

Steatite  is  the  mineralogical  name  applied  to  massive  talc. 
Soapstone  is  the  commercial  name  applied  to  the  same 
product.  Steatite  closely  resembles  serpentine  in  its  chemical 
composition,  mode  of  origin  and  in  some  of  its  physical  prop- 
erties. While  serpentine  is  of  varying  shades  of  green,  steatite 
is  usually  of  dark  bluish  gray  color.  It  may  be  grayish  green 
or  brownish  gray  in  color.  Its  hardness  varies  from  1  to  2.5 
and  its  specific  gravity  is  2.7. 

Composition. — Steatite  is  a  hydrous  silicate  of  magnesium 
formula  H2O,  3MgO,  -4SiO2.  If  the  rock  mass  contained  no 
other  minerals  than  talc  its  analysis  would  give  63.5  per  cent 
silica,  31.7  per  cent  magnesia  and  -i.S  per  cent  water.  This 
water  of  combination  is  liberated  only  at  a  red  heat. 

Talc  or  steatite  is  a  very  common  mineral  and  in  the  mas- 
sive form  it  constitutes  extensive  rock  masses  in  many  locali- 
ties. It  is  often  associated  with  serpentine,  talcose  schists, 
chlorite  schists,  siliceous  magnesite,  dolomite  and  gneiss.  It 
frequently  contains  crystals  of  dolomite,  breunnerite,  chryso- 
tile,  actinolite,  tourmaline,  magnetite,  pyrite  and  pyrrhotite. 

Origin. — Talc,  steatite  or  soapstone,  has  more  than  one 
mode  of  origin.  Its  most  frequent  derivation  is  by  the  alteration  of 
amphiboles  and  pyroxenes.  Carbonated  waters  acting  upon 
magnesium  silicates  can  develop  steatite  and  magnesite.  In 
the  case  of  a  calcium  magnesium  silicate,  calcite  is  formed  in 
addition  to  the  steatite.  Enstatite  and  tremolite  are  perhaps 
the  two  commonest  minerals  to  undergo  these  changes. 


SERPENTINE   AND    STEATITE  315 

The  talc  of  northern  New  York,  St.  Lawrence  County,'  is 
associated  with  crystalline  limestones.  C.  H.  Smyth  considers 
that  a  siliceous  limestone  was  first  formed  which  became  by 
metamorphism  a  tremolite-enstatite  schist.  This  schist  was 
in  part  subsequently  altered  to  talc. 

In  the  talc  mines  in  Lewis  County,  about  one  mile  from 
Natural  Bridge,  the  talc  is  associated  with  crystalline  limestones 
and  serpentine.  The  origin  here  is  from  the  alterations  of  the 
pyroxene  enstatite.  The  author  has  here  found  many  crystals 
with  the  structure  of  enstatite  well  preserved. 

In  the  northern  part  of  Vermont  the  talc  deposits  are  derived 
from  pyroxenite.  In  a  cross  section  of  the  peridotite  belt  in 
North  Troy,  the  central  portion  which  originally  consisted 
essentially  of  olivine  has  been  altered  to  serpentine.  The  ser- 
pentine is  flanked  upon  either  side  by  a  belt  of  steatite  which 
has  been  derived  from  pyroxenite.  The  steatite  is  flanked  upon 
either  side  by  sericite  schists.  C.  H.  Hitchcock  regards  the 
soapstones  of  Francestown,  New  Hampshire,  as  derived  by 
the  alterations  of  wholly  igneous  rocks.  These  may  have  been 
pyroxenites.  J.  H.  Pratt  considers  the  talc  deposits  of  North 
Carolina  to  have  been  derived  from  tremolite.  They  are  asso- 
ciated with  marble  which  is  capped  by  quartzite.  The  mineral, 
pyrophyllite,  which  is  a  hydrous  silicate  of  aluminum,  occurs 
in  the  same  region  and  may  be  mistaken  for  talc,  which  it 
closely  resembles.  It  is  used  commercially  to  a  smaller  extent 
than  talc. 

Characteristics. — Steatite  is  sufficiently  soft  to  be  scratched 
with  the  thumb  nail.  It  can  easily  be  sawn  into  blocks  and 
slabs  with  common  saws.  It  has  a  decidedly  soapy  feel.  It 
is  insoluble  in  the  mineral  acids,  which  fact,  together  with  its 
inferior  hardness,  renders  the  stone  especially  desirable  for 
table  tops  and  sinks  in  chemical  and  mineralogical  labora- 
tories. The  pseudomorphous  variety,  rensselaerite,  is  however 
decomposed  by  concentrated  H2SO4. 

AMERICAN  STEATITES 

Arkansas. — There  are  large  deposits  of  steatite  near  Benton, 
Saline  County.  The  stone  is  of  fine  compact  texture  and 
brecciated. 

California. — According  to  L.  E.  Aubury  soapstone  and  talc 
occur  in  23  counties  in  this  state.  The  best  known  quarries 
are  in  Butte  and  Los  Angeles  Counties,  where,  the  stone  has 
been  worked  for  structural  purposes. 


316  BUILDING    STONES   AND    CLAYS 

Maine. — Beds  of  soapstone  that  have  been  worked  to  some 
extent  occur  on  Orrs  Island  and  at  Jaquish  and  Harpswell  in 
Cumberland  County. 

Maryland. — The  soapstone  beds  of  this  state  have  been 
worked  to  a  limited  extent  in  Carroll  and  Montgomery 
Counties.  The  rock  mass  is  badly  jointed  and  only  blocks  of 
small  dimensions  can  be  obtained. 

Massachusetts. — Soapstone  quarries  have  been  operated  for 
many  years  in  Lynnfield  in  Essex  County.  This  stone  is  ex- 
tremely soft  when  first  quarried  but  hardens  upon  exposure 
to  the  atmosphere.  This  stone  has  found  use  in  sills,  risers, 
treads  and  stoves.  The  larger  quarries  of  the  state  are  situated 
at  North  Dana  in  Worcester  County,  and  these  have  been  ex- 
tensively worked  for  more  than  half  a  century. 

New  Hampshire. — The  extensive  beds  of  soapstone  in 
Francestown,  Grafton  County,  were  discovered  in  1794  and 
opened  in  1802.  They  have  been  in  operation  much  of  the 
time  for  more  than  a  century.  The  stone  is  fairly  uniform  and 
blocks  of  good  dimensions  have  been  obtained.  The  soapstone 
ic  of  uniform  dark  color.  Steatite  beds  also  occur  in  Haverill, 
Orford  and  Warren  in  the  same  county.  Some  quarries  have 
been  opened  and  worked  intermittently.  Other  beds  occur  in 
Canterbury  and  Weare  in  Merrimack  County,  and  in  Rich- 
mond in  Cheshire  County. 

New  York. — The  talc  deposits  of  St.  Lawrence  and  Lewis 
Counties  are  amongst  the  best  known  producers  of  this 
mineral  in  its  fibrous  form  in  the  United  States.  The  soap- 
stone  is  fairly  uniform,  tough  and  refractory. 

North  Carolina. — There  are  many  scattered  occurrences  of 
soapstone  in  the  southwestern  part  of  the  state.  The  Nante- 
hala  stone  from  Cherokee  County  is  a  pure  and  nearly  white 
compact  talc  which  is  generally  regarded  as  equal  to  the  best 
French  chalk  so  largely  used  by  tailors.  The  so-called  soap- 
stone  of  Deep  River  is  in  reality  pyrophyllite.  It  is  ground 
and  bolted  like  the  talc. 

Pennsylvania. — Steatite  has  been  quarried  for  many  years 
along  both  banks  of  the  Schuylkill  River  and  used  for  sills, 
steps,  furnaces,  stoves  and  fireplaces.  It  has  also  been  quar- 
ried on  the  west  side  of  the  Wissahickon  River. 

South  Carolina. — Beds  of  soapstone  are  known  to  occur  in 
at  least  ten  counties  in  South  Carolina,  yet  it  has  not  been 
extensively  quarried.  The  largest  quarries  have  been  opened 
in  Anderson  and  Pickens  Counties. 

Texas. — The  beds  of  soapstone  in  Texas  appear  to  be  inex- 


SERPENTINE   AND   STEATITE 


317 


haustible  in  quantity.     A  product  of  good  quality  is  obtained 
from  Llano  County. 

Vermont. — The  peridotite  belt  that  traverses  nearly  the 
entire  length  of  the  state  to  the  east  of  the  Green  Mountain 
axis  bears  numerous  outcrops  of  steatite,  in  scattered  occur- 
rences, that  have  resulted  from  the  alteration  of  pyroxenite. 
Some  of  these  beds  or  veins  are  of  greenish  white  color  and 
quite  pure  as  in  Moretown  and  Waterbury  in  Washington 
County,  while  others  are  of  the  common  dark  gray  color,  as 


Fig.  260. — Talc  mill,  Waterbury,  Vermont.  The  entrance  to  the 
mine  is  directly  above  the  left-hand  upper  corner  of  the  mill.  Photo, 
by  C.  H.  Richardson. 

in  the  more  northern  portions  of  the  state.  The  beds  in  the 
southeastern  portion  of  the  state  as  in  Grafton  are  associated 
with  gneiss  and  may  have  been  derived  from  minerals  of  the 
amphibole  family  bearing  calcium  and  magnesium.  (See  Fig. 
260.) 

Virginia. — Probably  the  best  known  steatite  beds  of  Vir- 
ginia are  those  of  Alberene  in  Albemarle  County.  This  stone 
is  uniformly  soft,  of  even,  fine  texture  and  rather  light  to  dark 
color.  Blocks  of  good  dimensions  are  easily  obtained  which 
are  sawed  into  slabs  for  table  tops,  sinks  and  stationary  wash- 


818 


BUILDING    STONES   AND    CLAYS 


PQ 


OT 


71 

rH     O 


SERPENTINE   AND    STEATITE 


319 


tubs.  This  stone  is  occasionally  traversed  by  narrow  white 
veins.  Samples  of  this  stone  immersed  for  48  hours  in  nitric 
acid  show  a  pitted  surface  due  to  a  solution  of  calcium  and 
iron  bearing  minerals.  There  are  at  least  four  distinct  belts 
of  soapstone  in  the  state.  Their  general  trend  is  to  the  north- 
east. Several  quarries  have  been  opened  in  these  beds  and 
the  product  is  of  good  quality.  (See  Fig.  261.) 


Fig.  262. — Alberene  stone  hoods,  table  tops,  sinks  and  shelving, 
installed  at  the  Bethlehem  Steel  Company's  plant,  South  Bethlehem, 
Pennsylvania.  By  courtesy  of  the  Alberene  Stone  Company. 

INDUSTRIAL  FACTS  ABOUT  STEATITE 

Uses. — Steatite  is  suited  in  many  ways  to  a  wide  variety  of 
applications.  It  is  one  of  the  most  indestructible  of  building 
stones  although  one  of  the  most  limited  in  its  uses  as  such. 
To  many  architects  and  engineers  it  is  too  somber  in  color  and 
too  greasy  in  feel  for  structural  purposes.  In  risers  and  treads 
it  has  often  proved  unsuitable.  It  wears  away  rapidly.  When 
it  contains  masses  of  serpentine  these,  with  their  greater  re- 
sistance to  abrasion,  stand  up  as  knobs  or  unsightly  protuber- 
ances upon  the  stone.  (See  Figs.  262,  263  and  264:.) 


320 


BUILDING    STONES   AND    CLAYS 


It  is  most  admirably  adapted  for  table  tops,  sinks,  vats, 
stationary  washtubs,  refrigerators,  fireplaces,  furnaces,  stoves, 
mantels,  fire  brick,  hearthstones,  warmers,  grills  and  griddles. 
The  waste  material  when  free  from  grit  can  be  pulverized  and 
used  as  a  lubricant  or  a  white  earth.  Large  quantities  are  con- 
sumed annually  in  the  manufacture  of  soap.  It  increases  the 
weight  of  the  soap  but  not  its  power  of  solution.  It  is  used 
extensively  as  a  filler  in  the  manufacture  of  paper  by  the  sul- 


Fig.  263. — Alberene  stone  table  tops,  shelves  and  hoods,  Melon 
Institute,  University  of  Pittsburg,  Pittsburg,  Pennsylvania.  By  cour- 
tesy of  the  Alberene  Stone  Company. 

phite  process.  Here  also  it  needs  to  be  free  from  grit.  It  is 
also  used  in  the  dressing  of  fine  skins  and  leather.  Shoe  and 
glove  dealers  consume  annually  an  appreciable  quantity  of 
this  commodity.  The  base  of  many  toilet  powders  is  talc. 
This  is  often  mixed  with  borax. 

Crayons  and  pencils  are  manufactured  from  the  creamy 
white  varieties.  French  chalk  is  a  pseudomorphous  variety 
that  is  imported  and  used  by  tailors.  The  fine  grained  and 
compact  varieties  are  manufactured  into  many  small  orna- 


SERPENTINE   AND    STEATITE 


321 


ments.  Tips  for  gas  burners  reveal  the  ease  with  which  the 
stone  may  be  manufactured  into  small  objects  of  considerable 
commercial  value.  Since  it  can  be  carved  into  fine  sharp  lines 
it  has  been  somewhat  a  favorite  for  grotesque  images.  Talc 
has  furthermore  been  used  as  the  body  of  paint  and  in  the 
manufacture  of  plaster. 


Fig.  264. — Alberene  stone  hood,  Melon  Institute,  Pittsburg,  Penn- 
sylvania. By  courtesy  of  the  Alberene  Stone  Company. 

The  largest  part  of  the  fibrous  talc  of  the  United  States 
comes  from  St.  Lawrence  County,  New  York,  and  enters 
largely  into  the  manufacture  of  paper  and  soap.  Virginia 
takes  the  lead  in  the  manufacture  of  articles  of  utility  from 
soapstone,  while  North  Carolina  stands  first  in  the  production 
of  pyrophyllite. 


322  BUILDING    STONES   AND    CLAYS 

REFERENCES 

A  few  references  are  here  given  to  some  of  the  more  im- 
portant papers  dealing  in  part  or  entirely  with  talc  and  steatite. 

Keith,  A.  Talc  Deposits  of  North  Carolina;  Bull.  213,  U.  S. 
Geological  Survey,  1903. 

Eckel,  E.  C.  Building  Stones  and  Clays;  J.  Wiley  and  Sons, 
1912. 

Jacobs,  E.  C.  Talc  and  the  Talc  Deposits  of  Vermont ;  Ann. 
Kept.  State  Geologist,  1914. 

Merrill,  G.  P.  Stones  for  Building  and  Decorating;  Second 
Edition,  J.  Wiley  and  Son,  New  York. 

Nevius,  J.  N.  Fibrous  Talc  in  St.  Lawrence  County,  New  York ; 
Engineering  and  Mining  Journal,  Vol.  67,  pp.  234,  235,  1899. 

Nevius,  J.  N.  The  Talc  Industry  of  St.  Lawrence  County,  New 
York;  51st  Ann.  Rept.  N.  Y.  State  Museum,  1899. 

Perkins,  G.  H.  Soapstone  in  Vermont;  Report  Vermont  State 
Geologist,  1900. 

Richardson,  C.  H.  Geology  of  Newport,  Troy  and  Coventry, 
Vermont;  Ann.  Rept.  State  Geologist,  1908. 

Smyth,  C.  H.  Report  of  the  Talc  Industry  of  St.  Lawrence 
County,  N.  Y. ;  15th  Ann.  Rept.  N.  Y.  State  Geologist,  Vol. 
1,  1897. 

Watson,  T.  L.  Talc  and  Soapstone  in  Virginia ;  Mineral  Re- 
sources of  Virginia,  Richmond,  1907. 


CHAPTER  VIII 

CLAYS 

Definition. — The  term  clay  is  one  that  scarcely  admits  of  a 
concise  definition.  It  is  one  of  the  many  substances  which  result 
from  the  decomposition  of  different  types  of  rock.  It  is 
generally  fine  grained,  unconsolidated,  and  when  wet  it  is  more 
or  less  plastic.  It  loses  the  property  of  plasticity  when  strongly 
heated  and  becomes  exceedingly  hard.  When  wet,  plastic  clays 
may  be  molded  into  any  desired  shape,  and  this  property  of  plas- 
ticity is  required  in  the  definition  of  commercial  clays.  Kaolinite 
is  often  referred  to  as  the  base  of  clays,  but  true  kaolinite  is  not 
plastic. 

Mineralogical  Composition. — Kaolinite  is  a  hydrous  silicate 
of  aluminum.  Its  formula  is  2H2O,  A12O3,  2SiO2.  It  is  often  asso- 
ciated with  its  ferric  equivalent,  nontronite,  whose  formula  is 
2H2O,  Fe2O3,  2SiO2.  Free  silica,  either  as  quartz  or  opal,  is 
present.  Also  many  fragments  of  undecomposed  minerals  and 
the  hydroxides  of  several  metals.  Kaolinite  is  a  stable  mineral 
but  nontronite  is  decomposed  by  acid  and  alkaline  solutions  into 
ferric  hydroxides  which  yield  limonite  as  a  final  product.  The 
mineral  composition  is  as  varied  as  the  types  of  rock  from  which 
the  clays  are  derived  and  the  amount  of  alteration  that  the  clays 
themselves  have  undergone.  As  the  clay  bed  is  hardened  by  pres- 
sure it  passes  into  a  shale.  The  fire  clays  of  the  coal  measures 
of  Pennsylvania  and  elsewhere  are  strictly  speaking  shales.  By 
pressure  sufficiently  intense  to  produce  fissility  shales  pass  into 
slates. 

Chemical  Composition. — Silica  and  alumina  are  essential  in 
all  clays.  The  oxides  of  iron  are  almost  invariably  present.  Lime, 
magnesia,  various  alkalies  and  sulphur  are  of  frequent  occur- 
rence. Analyses  of  clays  as  cited  later  must  vary  widely  on  ac- 
count of  these  differences  in  their  mineral  content  and  chemical 
composition. 

Size  of  Grains. — The  size  of  the  individual  particles  varies 
from  the  finest  of  dust  up  to  fragments  one-thousandth  of  a  milli- 
meter in  diameter.  These  finer  products  of  rock  decay  should 
predominate  over  the  grains  of  sand  that  are  visible  to  the  naked 
eye.  The  fineness  of  a  clay  may  be  roughly  determined  by  thor- 
oughly agitating  a  given  weight  of  clay  in  a  flat  bottomed 

323 


BUILDING    STONES   AND    CLAYS 

flask.  The  coarse  material  settles  quickly  to  the  bottom  of 
the  flask,  while  the  finest  particles  remain  in  suspension  sev- 
eral hours. 

Origin. — Clay  is  one  of  the  results  of  the  decomposition  of 
aluminous  minerals,  especially  the  feldspars  of  granites,  gneisses, 
porphyries  and  feldspathic  schists.  Vast  beds  of  kaolin  some- 
times occur  where  these  feldspathic  rocks  have  decomposed  on 
a  large  scale.  The  kaolinization  of  any  highly  feldspathic  rock 
may  yield  a  mass  of  nearly  pure  white  kaolin.  Quartz  and  scales 
of  mica  in  small  quantities  interfere  but  little  with  the  color  of 
the  resulting  product.  Kaolinite  is  the  mineralogical  name,  but 
when  the  mass  arrives  at  the  dignity  of  a  rock  formation  it  is 
termed  kaolin. 

Kaolinite  is  commonly  accepted  as  the  chief  residual  product 
of  feldspathic  decay  due  to  chemical  and  physical  causes.  Chem- 
ical agents  dissolve  out  the  soluble  constituents  of  rocks.  Organic 
acids  set  free  by  decomposing  vegetable  matter  are  solvents  of 
rock  constituents.  The  expansion  and  contraction  due  to  changes 
in  temperature  are  potent  agents  in  rock  disintegration.  H. 
Rosier  believes  that  kaolinite  is  produced  only  by  pneumato- 
lytic  action — that  is,  by  the  combined  influence  of  thermal 
waters  and  gaseous  emanations.  Clay  deposits  are  the  result 
of  two  sets  of  agencies.  The  one  is  chemical.  The  other  is 
mechanical. 

(1)  Residual  Clays.  —  These  clays   result    from   the   kaolin- 
ization   of    highly    feldspathic    rocks    with    the    product    remain- 
ing in  situ  or  in  close  proximity  to  the  place  of  origin.     They 
are    derived    from    the    decay    of    igneous    rocks,    the    decay    of 
shales  and  slates  and  the  decay  of  argillaceous  limestones. 

(2)  Transported    Clays.  —  Such    material    is    borne    mostly 
from  its  place  of  origin  by  the  agency  of  rivers.     In  certain 
instances  it  is  transported  by  the  agency  of  glaciers  and  in 
others   by   the    winds.      These    may    be    subdivided    into    (a) 
marine  clays  that  are  still  soft,  shales  and  slates.     These  were 
all  formed  in  salt  water  basins,     (b)    Stream  clays  that  have 
been  deposited  along  brooks  and  rivers.     Such   deposits  are 
more  or  less  sandy  for  they  often  represent  deposits  formed 
by  streams  during  their  periods  of  overflow,     (c)   Lake  clays 
which  were  laid  down  on  the  areas  bordering  the  Great  Lakes 
during  their  earlier  stages  of  existence.     They  have  also  been 
deposited  in  many  small  lakes  and  ponds  in  the  area  covered 
by   the   great  ice   mantle   of   the   glacial   epoch,      (d)    Glacial 
clays  which  have  been  formed  in  part  by  the  scouring  action 
of    the    glaciers,    transported    and    deposited    by    them.      (e) 


CLAYS  325 

Eolian  clays  which  have  been  transported  by  the  agency  of 
the  wind  and  the  deposits  influenced  somewhat  in  certain 
cases  by  temporary  streams. 

Residual  Clays. — Such  clays  remain  in  or  near  the  place 
where  the  original  rock  is  disintegrated.  Pegmatite  veins  are  es- 
pecially prone  to  yield  kaolinite  in  their  decomposition.  Gneisses, 
feldspathic  schists  and  even  dolomites  have  produced  them.  Such 
clays  retain  in  their  lower  portions  many  angular  fragments  of 
undecomposed  minerals,  while  the  number  of  such  fragments 
will  increase  as  the  parent  rock  is  approached.  The  depth  which 
residual  clays  attain  depends  upon  the  amount  of  work  done  by 
both  chemical  and  mechanical  agents  and  the  angle  of  slope  upon 
which  the  clays  rest.  Valleys  and  flats  are  their  especial  home, 
where  they  sometimes  assume  great  thickness. 

Sedimentary  Clays. — Sedimentary  or  transported  clays  are 
those  that  no  longer  rest  upon  the  parent  rocks  from  which  tbev 
have  been  derived.  They  have  been  transported  by  various 
agencies  to  regions  more  or  less  remote  from  their  place  of  de- 
rivation and  deposited  along  river  beds,  in  lakes  or  on  the  floor  of 
the  sea.  They  bear  no  genetic  relation  to  the  rocks  beneath 
them.  A  series  of  beds  of  similar  or  of  dissimilar  character  may 
appear  within  a  given  area.  These  may  be  overlain  with  sedi- 
ments consisting  essentially  of  sand  or  mixed  sediments  of  suf- 
ficient depth  to  compress  the  clay  beds  into  shales. 

Glacial  Clays. — Glacial  clays,  as  the  name  implies,  comprise 
the  rock  flour  that  has  been  deposited  beneath  or  in  front  of 
glaciers.  They  owe  their  position  to  the  transporting  power  of 
glaciers.  They  owe  their  origin  to  the  engraving  and  grinding 
tools  in  the  lower  portion  of  the  glacier.  Their  composition 
varies  markedly  from  the  other  clays,  for  they  were  formed  under 
conditions  that  protected  them  in  some  measure  from  the  chemical 
agents  of  the  atmosphere.  They  contain  more  soluble  matter 
than  the  clay  formed  by  normal  weathering  agencies,  whether 
residual  or  transported.  These  differences  will  be  conspicuous 
in  the  analyses.  Glacial  clays  are  of  considerable  importance  but 
of  somewhat  limited  distribution. 

Eolian  Clays. — Such  clays  are  often  called  wind-borne  clays 
because  they  are  considered  by  many  scientists  to  have  been 
transported  and  deposited  by  winds.  They  are  also  called  loess 
clays.  In  chemical  composition  they  bear  a  close  resemblance  to 
glacial  clays.  They  usually  contain  calcium  carbonate  in  appre- 
ciable amounts.  They  are  of  limited  extent  and  minor  impor- 
tance. The  striking  peculiarities  of  the  loess  clays  are  their  light 
color,  their  extremely  fine  state  of  subdivision,  the  angularity  of 


326  BUILDING    STONES   AND    CLAYS 

their  constituents,  the  absence  of  stratification  in  the  beds,  to- 
gether with  their  coherence  and  porosity. 

Origin. — F.  Richthofen  considers  the  loess  of  China  as  an 
eolian  deposit.  In  Central  Asia  wind  blown  dust  comes  to  rest 
wherever  it  is  entangled  and  protected  by  the  grasses  of  the 
steppes.  Small  temporary  streams  that  result  from  showers  aid 
in  the  accumulation  of  loess  in  valleys  and  other  depressions. 

The  adobe  deposits  of  the  Great  Basin  contain  the  finer  pro- 
ducts of  subaerial  erosion  of  mountain  slopes,  and  may  even 
be  commingled  with  dust  of  volcanic  origin.  This  material  was 
deposited  in  playa  lakes  whose  beds  are  dry  during  a  great 
part  of  the  year.  The  loess  of  the  Missouri  and  upper  Mississ- 
ippi valleys  consist  mainly  of  the  dust  from  river  silt  that  has 
been  left  on  the  dried  mud  banks  in  times  of  low  water. 

W.  J.  McGee  considers  the  loess  of  Iowa  as  a  glacial  silt  that 
was  deposited  along  the  margin  of  glaciers  during  the  glacial 
period.  W.  F.  Hume  regards  the  Russian  loess  as  glacial  silt 
that  has  accumulated  in  part  by  the  agency  of  the  winds  and 
in  part  by  floods.  T.  C.  Chamberlin  considers  certain  loess  to 
be  derived  from  both  glacial  and  eolian  influences. 

Geological  Horizon. — Clays  belong  to  the  younger  geologi- 
cal formations.  They  range  from  the  Carboniferous  to  the 
Pleistocene. 

PHYSICAL  PROPERTIES 

The  physical  properties  that  effect  the  commercial  values 
of  clays  are  plasticity,  fusibility,  color,  slaking,  tensile  strength, 
air  shrinkage  and  fire  shrinkage. 

Plasticity. — Plastic  clays  form  a  pasty  mass  when  mixed 
with  the  proper  amount  of  water  so  that  they  may  be  molded  into 
any  desired  shape.  They  retain  their  shape  when  burned.  A  clay 
may  be  too  plastic  or  fat  to  work  well.  Sand  must  then  be  added 
to  decrease  the  plasticity.  A  clay  may  also  be  too  lean  for  com- 
mercial purposes  without  the  addition  of  some  highly  plastic  clay. 
Ground  shales  are  not  as  plastic  as  clays  derived  from  the  same 
shales  by  the  disintegrating  agents  of  the  atmosphere  for  grinding 
does  not  thoroughly  disintegrate  the  shale. 

Plastic  clays  have  great  efficiency  in  the  absorption  of  water. 
Nonplastic  or  lean  clays  are  inferior  in  this  respect.  The  plas- 
ticity of  clays  is  due  to  the  colloidal  substances  they  happen  to 
contain.  The  colloids,  or  hydrogels,  hydroxides  of  alumina  and 
iron,  are  common  constituents.  Similar  hydrogels  of  manganese 
and  copper  oxides  are  frequently  present.  The  colloidal  com- 


CLAYS  327 

plexes  of  aluminum  and  iron  silicates  and  humus  behave  in  much 
the  same  manner. 

Fusibility. — The  fusibility  of  clays  depends  in  a  large  de- 
gree upon  the  amount  of  fluxes  they  contain.  These  are  generally 
lime,  magnesia,  oxides  of  iron,  and  various  alkalies.  The  size 
of  the  individual  grains  in  the  clay  enters  into  the  problem.  Other 
things  being  equal  fine  grained  clays  will  fuse  at  lower  tempera- 
tures than  the  coarse  grained  clays.  Common  brick  clays  will 
fuse  at  temperatures  varying  from  1,090  to  1,250  degrees  C. 
The  range  of  fusion  of  stoneware  clays  falls  between  1,410  and 
1,510  degrees  C.  Fire  clays  become  viscous  between  1,750  and 
1,790  degrees  C.  The  fusibility  of  any  clay  can  be  determined 
by  comparison  with  the  fusion  points  in  the  standard  set  of  Segar 
cones.  This  set  consists  of  58  cones  which  range  in  fusion  from 
590  degrees  C,  to  1,850  degrees  C. 

Color. — The  color  of  clays  is  not  always  a  safe  guide  as  to 
commercial  value.  Clays  colored  red  and  brown  by  the  oxides  and 
hydrous  oxides  of  iron  suggest  a  low  fusion  point,  for  these 
oxides  serve  as  fluxing  material  in  the  burning  of  the  clay.  Black 
clays  free  from  an  iron  content  or  with  only  a  small  amount  of 
iron,  will  burn  white  or  a  creamy  white.  If  the  iron  oxides  are 
present  in  appreciable  quantities  even  black  clays  will  burn  red. 
Clays  containing  large  quantities  of  organic  matter  may  be  slowly 
burned  into  satisfactory  bricks. 

Slaking. — This  is  the  property  a  clay  possess  of  falling  apart 
when  thrown  into  water.  The  more  rapidly  a  clay  slakes  the 
more  readily  it  can  be  mixed  and  the  more  easily  it  is  washed. 
Washing  is  often  necessary  by  mechanical  means  to  free  a  clay 
from  injurious  constituents.  Dense  clays  slake  slowly.  Many 
shales  refuse  to  slake  when  thrown  into  water  but  disintegrate 
completely  upon  sufficient  exposure  to  the  atmosphere. 

Tensile  Strength. — This  property  expresses  the  resistance  to 
rupture  that  air  dried  clays  will  exhibit.  Plastic  clays  usually 
show  a  higher  tensile  strength  than  lean  clays.  A  high  tensile 
strength  enables,  a  clay  to  resist  cracking  while  in  the  process  of 
drying.  It  also  withstands  harder  usage. 

Clays  and  shales  show  a  wide  variation  in  their  cohesiveness 
on  account  of  the  variations  in  their  mineral  composition.  Sandy 
clays  as  well  as  kaolins  are  usually  of  low  tensile  strength.  The 
tensile  strength  of  different  kinds  of  clays  is  here  given  to  show 
this  wide  range.  The  strength  is  stated  in  terms  of  pounds  per 
square  inch. 


328  BUILDING    STONES   AND    CLAYS 

Lb.  Per  Sq.  In. 

Kaolins   5-  20 

Paleozoic  shales    . 60-  80 

Brick  clays 80-150 

Pottery    clays     150-200 

Very  plastic  clays   200-400 

The  tensile  strength  of  clay  is  determined  in  the  same  manner 
as  the  tensile  strength  of  cement.  The  clay  is  fashioned  into 
briquettes  which  are  then  air  dried  in  a  'warm  room  and  subse- 
quently broken  in  testing  machines.  If  the  briquettes  are  not 
uniform  in  size  and  different  methods  are  employed  in  drying 
the  results  obtained  may  be  misleading. 

Air  Shrinkage. — This  term  refers  to  the  decrease  in  size  of  a 
given  mass  of  clay  during  the  process  of  air  drying.  It  is  the 
loss  in  volume  sustained  by  clays  during  the  evaporation  of  the 
water  used  in  mixing  the  material.  The  percentage  of  air  shrink- 
age stands  in  direct  relation  to  the  amount  of  water  absorbed  by 
the  clay  in  the  process  of  mixing  and  tempering.  The  amount  of 
absorption  depends  upon  the  plasticity  of  the  clay.  The  more 
plastic  t'he  clay  the  more  water  it  absorbs  and  therefore  the 
greater  will  be  its  air  shrinkage.  Some  lean  or  sandy  clays  show 
only  from  1  to  2  per  cent  of  shrinkage  while  plastic  clays  vary 
from  8  to  10  per  cent. 

Clays  may  be  either  too  lean  or  too  fat  for  commercial  pur- 
poses. The  more  sandy  clays  need  to  be  mixed  with  some  highly 
plastic  clay.  Clays  that  are  too  plastic  need  the  addition  of  some 
sandy  material.  The  practical  problem  is  to  secure  the  clay  that 
will  show  the  proper  air  shrinkage.  The  greater  the  decrease  in 
volume  during  drying  the  greater  is  the  danger  of  the  various 
products  cracking  or  warping.  Products  manufactured  from 
highly  plastic  clays  must  be  dried  carefully  and  slowly  to  prevent 
these  ill  effects.  The  ideal  clay  or  mixture  of  clays  will  have  a 
low  air  shrinkage  and  will  withstand  rapid  drying.  The  drying 
will  begin  by  the  evaporation  of  the  mixing  water  as  soon  as  the 
molded  product  is  taken  from  the  machine.  It  is  not  all  evap- 
orated before  the  products  are  placed  in  the  kiln  for  burning. 
The  last  of  the  mixing  water  is  expelled  during  the  early  stages 
of  burning  the  products.  The  large  quantities  of  water  vapor 
often  seen  issuing  from  the  chimneys  of  kilns  represent  a  part 
of  the  water  used  in  mixing  the  materials  and  not  the  water  of 
crystallization  in  the  particles  of  kaolinite  in  the  clay.  The 
process  of  expelling  the  water  is  known  as  water-smoking. 

Fire  Shrinkage. — Fire  shrinkage  is  the  decrease  in  volume 
that  clay  products  undergo  during  the  process  of  burning  in  the 
kiln.  It  occurs  after  all  of  the  water  and  carbon  dioxide  have 


CLAYS 

been  expelled.  It  commences  at  the  time  the  various  products 
reach  a  dull  redness.  Sandy  clays  show  a  fire  shrinkage  varying 
from  2  to  3  per  cent  and  highly  plastic  clays  from  15  to  20  per 
cent.  Fire  shrinkage  in  clay  produces  may  be  diminished  by  the 
addition  of  sand  to  the  mixture.  If  too  much  sand  is  added  the 
products  may  expand  at  high  temperatures. 

CHEMICAL  COMPONENTS 

The  manufacturer  of  clay  products  considers  the  physical 
properties  of  clays  of  far  greater  significance  to  him  than  the 
chemical  composition.  The  former  are  capable  of  easy  interpre- 
tation by  him  while  he  fails  in  many  cases  to  utilize  facts  revealed 
in  chemical  analysis.  The  analysis  is  always  of  value.  It  is  of 
greater  significance  in  high  grade  clays. 

The  quantitative  analysis  reveals  the  percentage  of  silica, 
alumina,  ferric  and  ferrous  oxides,  lime,  magnesia,  potash  and 
soda  present  in  the  clay.  Titania,  manganese  oxide,  phosphoric 
acid  and  sulphuric  acid  are  often  present  in  small  quantities  and 
not  always  determined  in  the  ordinary  quantitative  analysis.  The 
former  list  of  clay  constituents  either  increases  or  decreases  the 
fusibility  of  the  clay  products  according  to  whether  they  are 
fluxing  or  nonfluxing  materials.  Iron  oxides,  lime,  magnesia, 
potash  and  soda  are  regarded  as  fluxing  materials,  while  silica 
and  alumina  are  refractory  or  nonfluxing  constituents. 

Kaolinite. — This  mineral,  which  is  a  hydrated  silicate  of 
aluminum,  is  regarded  as  present  in  varying  proportions  in  all 
clays.  It  is  infusible  before  the  blowpipe  for  it  is  highly  refrac- 
tory. Its  fusion  is  easily  effected  in  the  presence  of  fluxes. 

Silica. — The  silica  present  in  clays  comprises  (1)  Free  silica, 
or  quartz  particles.  (2)  The  silica  combined  with  the  bases  as 
represented  by  the  feldspars,  micas,  amphiboles,  pyroxenes  and 
garnets  whose  finely  comminuted  fragments  remain  in  the  various 
clays.  (3)  The  silica  contained  in  the  hydrous  silicate  of  alumi- 
num, kaolinite. 

The  free  quartz  or  true  sand  is  present  in  varying  proportions 
in  all  clays.  It  is  insoluble  in  the  mineral  acids  and  practically 
insoluble  in  caustic  alkalies.  At  low  temperatures  it  is  refractory, 
but  at  high  temperatures  in  the  presence  of  alkalies  it  is  a  fluxing 
material.  Its  presence  diminishes  the  air  shrinkage,  fire  shrink- 
age and  plasticity  of  clays,  while  its  tendency  is  to  increase  the 
porosity  of  the  finished  products.  The  anhydrous  silicates  are 
often  grouped  with  the  sand  and  incorrectly  called  free  silica. 

Alumina. — The  alumina  in  clays  is  of  two  kinds.  (1)  The 
alumina  combined  with  the  silica  in  the  feldspar,  micas,  aluminous 


330  BUILDING    STONES   AND    CLAYS 

amphiboles  and  pyroxenes  together  with  the  alumina  in  the  gar- 
nets. (2)  The  essential  alumina  in  the  kaolinite  particles.  The 
aluminum  silicates  present  in  the  clays  may  be  regarded  as  re- 
fractory or  nonfluxing  constituents. 

Iron. — Iron  bearing  minerals  are  common  constituents  in 
ordinary  clays.  The  most  prevalent  iron  minerals  are  hematite, 
limonite  and  their  homologs.  Iron  may  be  present  as  a  silicate 
wherever  grains  of  glauconite  or  garnets  appear  in  the  clays.  It 
is  found  in  some  clays  as  the  carbonate,  siderite,  and  in  clay  iron 
concretions.  It  may  also  appear  as  the  sulphide,  pyrite,  and  as  a 
phosphate  in  vivianite. 

The  function  of  the  iron  particles  in  the  clay  is  two-fold.  (1) 
They  all  serve  as  a  flux  and  therefore  lower  the  fusion  point  of 
the  clays  containing  them.  (2)  They  serve  as  coloring  agentsr 
not  only  for  the  clays  before  molding  but  in  the  color  of  the  fin- 
ished products. 

Hematite  imports  a  red  color  to  the  original  clays.  Limonite 
a  reddish  brown  or  even  a  yellow  color,  depending  upon  the  de- 
gree of  hydration  of  the  iron  and  the  amount  of  the  hydrated 
oxides  present.  Minute  grains  of  pyrite,  although  a  pale  brass 
yellow  themselves,  tend  to  produce  a  gray.  When  grains  of 
vivianite  become  sufficiently  abundant  the  color  is  a  bluish  gray. 
Glauconite  grains  tend  to  produce  a  green  coloration  in  clays  and 
shales.  The  green  color  of  the  Vernon  shales  of  central  New 
York  is  due  in  part  to  the  presence  of  glauconite. 

The  presence  of  the  oxides  and  the  hydrous  oxides  of  iron  in 
moderate  amounts  in  clay  is  not  objectionable  unless  a  white  or 
creamy  white  ware  is  desired.  Pyrite  is  an  objectionable  con- 
stituent for  it  yields  sulphuric  acid  in  the  process  of  burning. 
This  tends  to  make  the  finished  products  poor.  If  present  as 
crystals  or  granular  masses  these  should  be  extracted  before  the 
clay  is  molded.  If  not  extracted  the  clay  should  be  finely  crushed 
so  as  to  reduce  all  lumps  bearing  pyrite  to  a  fine  state  of  sub- 
division else  the  lumps  will  melt,  swell  and  throw  off  pieces  of 
the  ware  during  the  process  of  burning.  Whenever  iron  is 
present  in  the  clay  as  the  mineral  siderite,  or  as  clay  iron  concre- 
tions bearing  manganese,  these  should  also  be  removed  from  the 
clay  either  in  the  process  of  mining  or  in  preparing  the  clay  for 
mixing.  The  presence  of  these  concretions  in  the  molded 
products  tends  to  form  blisters  during  the  process  of  burning. 

In  whatever  compound  the  iron  is  present  in  the  original  clay 
it  will  be  converted  into  the  ferric  condition,  if  not  ferric  before 
burning,  during  the  process  of  burning.  This  holds  especially 
true  when  the  atmosphere  of  the  kiln  is  free  from  smoke  so  that 


CLAYS  331 

it  becomes  an  oxidizing  agent.  During  the  later  stages  of  burn- 
ing a  part  of  the  iron,  if  not  all,  unites  with  other  elements  in  the 
formation  of  complex  silicates. 

In  the  process  of  burning  iron  bearing  clays  small  quantities  of 
iron  tend  to  produce  a  buff  colored  product.  Large  quantities 
of  iron  in  the  clay  will  produce  a  red  coloration.  The  intensity 
of  the  color  is  affected  by  the  higher  temperatures.  When  clays 
are  rich  in  iron  content  they  are  often  limed  until  the  lime  is  in 
excess  of  the  iron  in  order  that  a  buff  colored  product  may  be 
obtained. 

Lime. — Lime  is  present  in  some  form  in  nearly  all  clays.  It 
is  usually  derived  from  the  common  minerals  calcite  and  dolomite. 
In  rare  cases  it  may  have  been  derived  from  labradorite,  a  horn- 
blende, augite  and  even  garnet.  Its  presence  serves  as  a  fluxing 
agent  in  the  burning  of  the  products.  It  increases  the  rate  of 
softening  of  the  clay  under  fire.  It  destroys  the  red  color  nor- 
mally imparted  by  iron  to  various  wares.  Its  presence  can  be 
easily  detected  by  effervescence  with  dilute  HC1. 

The  form  in  which  calcium  carbonate  is  present  in  clays  is  a 
matter  of  considerable  importance.  When  it  occurs  in  a  fine 
state  of  subdivision  it  is  not  injurious  for  many  purposes.  When 
it  occurs  in  lumps  or  pebbles  it  should  either  be  removed  in  the 
mining  of  the  clay  or  finely  crushed  and  intimately  mixed  with 
the  clay  before  molding  and  burning.  W7hen  present  in  lumps 
the  expulsion  of  the  carbonic  acid  during  the  process  of  burning 
produces  blisters  in  the  ware.  These  aggregations  may  also  ab- 
sorb moisture  after  the  product  has  been  burned  and  thereby 
split  off  particles  of  the  ware. 

Calcareous  clays  bearing  20  per  cent  or  more  of  carbonate  of 
lime  may  be  used  in  the  manufacture  of  common  brick,  earthen 
ware,  drain  tile  and  terra  cotta.  They  are  not  suited  for  the 
manufacture  of  paving  brick,  stone  ware,  sewer  pipe  or  vitrified 
ware  in  general.  Calcareous  clays  are  used  to  a  considerable 
extent  in  the  manufacture  of  Portland  cement. 

Magnesia. — Fuller's  earth  includes  many  varieties  of  unc- 
tuous clays  of  gray  and  dark  green  color.  It  is  only  in  part  Breit- 
haupt's  smectite  which  sometimes  carries  4.89  per  cent  magnesia. 
Kaolinite  is  a  common  constituent  in  these  clays.  Save  in 
fuller's  earth  all  varieties  of  clay  bear  an  inappreciable  quan- 
tity of  magnesia.  The  objections  to  large  quantities  of  mag- 
nesium carbonate  are  the  same  as  those  mentioned  for  similar 
quantities  of  calcium  carbonate. 

Alkalies. — This  term  includes  the  salts  of  both  potash  and 
soda.  They  are  present  in  nearly  all  clays.  They  are  most  fre- 


332  BUILDING    STONES    AND    CLAYS 

quently  derived  from  various  members  of  the  feldspar  or 
mica  families.  All  orthoclase  and  muscovite  are  rich  in 
potassium.  Albite  is  the  feldspar  with  the  highest  percentage  of 
sodium.  The  alkalies  of  some  residual  clays  have  been  attributed 
in  part  to  various  amphiboles,  pyroxenes  and  even  garnets.  The 
presence  of  these  alkalies  as  necessary  constituents  of  feldspathic 
grains  serves  as  a  fluxing  agent.  Some  feldspar  is  usually  added 
to  kaolin  in  the  manufacture  of  porcelain,  earthenware  and  other 
wares  burning  to  a  white  dense  body.  Albite  is  often  added  to 
white  kaolinite  in  the  manufacture  of  pure  white  porcelain.  The 
alkalies,  however,  do  not  influence  the  color  of  the  finished 
product.  It  is  rather  the  impurities  in  the  kaolin  that  play  this 
role. 

Titanium  Dioxide. — Rutile,  TiO2,  is  rather  widely  scattered 
in  minute  grains  or  crystals  in  both  igneous  and  sedimentary 
rocks.  As  it  is  insoluble,  and  in  the  highest  state  of  oxidation 
for  titanium,  these  particles  appear  in  minute  quantities  in  many 
clays,  but  nowhere  in  a  quantity  to  warrant  extraction  of  the 
titanium  content.  Small  quantities  of  titania  are  often  added  to 
produce  an  ivory  tint  in  porcelain. 

Manganese  Oxide. — Manganese  frequently  appears  in  minute 
quantities  in  clays.  Its  presence  may  be  attributed  to  the  decom- 
position of  manganese-bearing  silicates.  In  these  minute  quan- 
tities that  are  not  determined  in  many  analyses  of  clays  it  is  not 
injurious.  The  greatest  danger  appears  to  be  when  it  is  present 
in  the  clay  iron  concretions  and  these  nodular  masses  are  not 
removed  in  the  mining  of  the  clay  or  crushed  finely  before  mixing 
the  clay  for. molding.  The  ill  effect  of  these  nodules  has  already 
been  cited  under  the  caption  of  iron.  Small  quantities  of  man- 
ganese oxide  can  produce  a  violet  tint,  larger  amounts  a  brown, 
while  an  excess  will  produce  a  jet  black  coloration  as  seen  in  door 
knobs. 

Sulphuric  Acid. — This  product  is  derived  from  the  burning 
of  clays  rich  in  sulphides  and  the  resulting  wares  are  always  poor. 

Water. — There  are  two  kinds  of  water  in  all  clays.  (1)  Hy- 
groscopic moisture  which  is  mechanically  mixed  with  the  clay 
grains.  (2)  \Yater  of  combination  which  is  essential  in  all 
kaolinite.  Shales  usually  contain  only  a  small  percentage  of 
mechanically  combined  water,  while  some  clays  carry  from  30  to 
40  per  cent  of  hygroscopic  moisture.  The  expulsion  of  this  mois- 
ture during  the  process  of  air  drying  is  accompanied  with  a 
shrinkage  of  the  mass.  Its  complete  expulsion  is  effected  during 
the  early  stages  of  burning  the  products  in  the  kiln.  Air  shrink- 


CLAYS  333 

age  ceases  when  all  the  particles  are  brought  in  contact  with  each 
other. 

Hygroscopic  moisture  may  be  injurious  in  clays  for  two 
reasons.  ( 1 )  It  may  dissolve  soluble  salts  contained  in  the  clay 
and  bring  to  the  surface  an  undesirable  efflorescence,  or  white 
coating.  (2)  If  this  moisture  is  expelled  too  rapidly  in  the 
process  of  burning  the  ware  will  blister. 

Chemically  combined  water  is  present  in  all  clays.  Pure 
kaolinite  bears  14  per  cent  of  such  water.  Its  presence  is  further 
due  to  the  hydrated  oxides  of  iron  and  to  hydrous  silicates  that 
happen  to  be  present  in  the  clay.  It  is  liberated  only  at  a  red 
heat  and  is  accompanied  with  a  second  shrinkage  in  the  mass. 

Organic  Matter. — Varying  amounts  of  organic  matter  are 
usually  present  in  transported  clays.  It  comprises  the  finely 
divided  plant  tissues,  and  in  some  instances  larger  portions  of 
plant  remains,  that  have  suffered  deposition  along  with  the  clayey 
matter.  The  presence  of  organic  matter  affects  the  clay  in  three 
ways.  (1)  It  affects  the  color  of  the  clay,  or  shale.  (2)  It  reduces 
its  plasticity.  (3)  It  lowers  its  power  of  absorption.  The  presence 
of  organic  matter  does  not  affect  the  color  of  the  finished  products 
for  it  is  usually  all  consumed  in  the  process  of  burning  the  various 
wares.  In  some  cases  a  vitrified  zone  forms  around  the  center 
which  still  contains  the  carbon.  The  carbon  thus  encircled  may 
continue  to  burn  and  liberate  gases  which  bloat  the  brick.  If  the 
burning  is  not  accompanied  with  a  temperature  sufficiently  high 
to  bloat  the  brick  then  there  remains  within  the  brick  a  black  core. 

Chemical  Analysis.  —  A  few  analyses  are  appended  as  a 
matter  of  reference.  They  throw  but  little  light  on  the  behavior 
of  clays  in  the  process  of  manufacture  of  the  various  wares,  save 
where  the  percentage  of  impurities  becomes  especially  pro- 
nounced. 

1.     Analysis  of  a  typical  sample  of  orthoclase. 

Silica,   SiO2    64.6% 

Alumina,    A10O3    . 18.5 

Potassa,  ICO  16.9 


100.0 
2.     Analysis  of  a  typical  kaolinite. 

Silica,   SiO2    46.2 

Alumina,    A1,O,    39.8 

Water,  H2O   13.9 

99.9 


334:  BUILDING    STONES   AND    CLAYS 

3.  Analysis  of  a  typical  pholerite  which  stands  next  to  kaolin- 
ite  in  importance  amongst  the  hydrous  silicates  derived  from  the 
decomposition  of  orthoclase. 

Silica,    SiO2    39.3 

Alumina,  A10O3   45.0 

Water,  H2O" 15.7 

100.0 

4.  This  analysis  represents  the  composition  of  a  residual  clay 
from  Greenville,  Georgia.    The  analysis  is  taken  from  Bulletin  9, 
Georgia  Geological  Survey,  p.  315.     This  clay  was  derived  from 
granite. 

Silica,  SiO2 51.29 

Alumina,  A12O3   29.69 

Ferric  oxide,  Fe2O3 6.33 

Ferrous  oxide,  FeO,  and  Lime,  CaO.  .  .      0.07 

Magnesia,    MgO    0.14 

Potassa,  K2O  . 1.50 

Soda,  Na3O    1.12 

Combined  water,  H2O   10.36 

100.50 

5.  Number  5  represents  the  average  of  four  analyses  of  re- 
sidual clays  from  shale  from  Hot  Springs,  Arkansas.    The  analy- 
sis was  made  by  George  Steiger  and  taken  from  Bulletin  285, 
U.  S.  Geological  Survey,  p.  409. 

Silica,  Si02 \ 71.91 

Alumina,  A12O3   16.24 

Iron  oxide,  Fe2O3   1.79 

Lime,  CaO    0.18 

Magnesia,  MgO 0.88 

Alkalies,  K2O,  Na2O 3.27 

Combined  water,  H2O    4.39 

98.66 

6.  Analysis  of  residual  clay  derived  from  limestone,  Morris- 
ville,   Calhoun   County,   Alabama.     The  analysis   is  taken    from 
Bulletin  52,  U.  S.  Geological  Survey,  p.  40. 

Silica,  SiO2 55.42 

Alumina,  A10O3   22.17 

Iron  oxide,  Fe,O3   8.30 

Lime,  CaO   0.15 

Magnesia,  MgO 1.45 

Alkalies,  K0O,  Na2O 2.49 

Water,  H26   9.86 

99.84 


CLAYS  335 

7.     Analysis  of  a  marine  clay  from  Thomaston,  Maine.     The 
analysis  was  made  by  W.  T.  Schaller. 

Silica,  SiO2 62.80 

Alumina,  A12O3  and  small  amounts  of 

titanic  acid,  TiO2    18.23 

Iron  oxides,  Fe2O3,  FeO   6.40 

Lime,  CaO   0.88 

Magnesia,  MgO 1.58 

Potassa,  K2O 3.05 

Soda,  Na2O    1.46 

Combined  water,  H2O   4.39 

Moisture    .  1.31 


100.10 
8.     The  following  analysis  of  a  stream  clay  from  Catskill,  New 

York,   is  taken   from   Bulletin   35,    New   York   State   Museum, 

p.  702. 

Silica,  SiO2 52.73 

Alumina,  A12O3   22.25 

Iron  oxides,  Fe2O3,  FeO 7.69 

Lime,  CaO   1.48 

Magnesia,  MgO 3.20 

Potassa,  K2O  4.28 

Soda,  Na2O 2.22 

Carbon  dioxide  and  combined  water.  .       4.91 


98.76 

9.     Analysis  of  loess  clay  from  St.  Louis,  Missouri.     Analysis 
quoted  from  Building  Stones  and  Clays,  E.  C.  Eckel. 

Silica,  SiO2 73.92 

Alumina,  A12O3   11.65 

Iron  oxide,  Fe2O3   4.74 

Lime,  CaO   1.43 

Magnesia,  MgO 0.60 

Alkalies,  K2O,  Na2O 3.13 

Combined  water,  H2O   3.08 

98.55 


CHAPTER  IX 

MINING  AND  WASHING  CLAYS 
MINING 

The  methods  utilized  in  mining  clay  and  shale  are  essentially 
the  same.  \Yhere  the  deposits  are  large  and  the  clays  of  uniform 
texture  and  composition  the  process  is  simple.  If  the  clays  are 
shallow,  of  limited  distribution  and  of  many  varieties  the  process 
may  be  rendered  somewhat  complex. 

There  are  two  quite  different  methods  of  mining  the  clays. 
(1)  Quarrying,  open-pit  work  as  it  is  sometimes  called.  (2)  Un- 
derground working. 

Quarrying. — The  method  often  observed  by  the  writer  at  the 
smaller  brick  plants  in  northern  New  England  is  to  remove  the 
soil  overlying  the  clay  by  means  of  a  spade  and  wheelbarrow,  or 
in  larger  deposits  with  a  sp.'in  of  horses  and  a  scraper.  The  clay 
is  then  quarried  by  means  of  a  pick  and  shovel.  The  work  is 
open  cut  as  in  quarrying  building  stones.  (See  Fig.  2(55.) 

There  are  often  several  different  benches  of  the  clay  which  are 
being  mined  or  quarried  at  the  same  time.  Their  appearance  is 
not  altogether  unlike  the  effect  produced  in  a  granite  quarry  by 
the  different  sheets  of  granite  on  the  different  levels  of  the  quarry 
foor.  This  method  is  employed  in  the  majority  of  the  clay  work- 
ing industries  of  the  United  States.  It  is  applicable  in  all 
cases  where  the  deposits  are  shallow,  where  they  are  of  some- 
what limited  extent,  where  the  use  of  a  steam  shovel  is  imprac- 
tical and  where  the  clays  vary  in  composition  so  that  they  can 
not  be  advantageously  mixed.  (See  Fig.  206. ) 

Wheel  Scraper. — The  wheel  scraper  is  used  to  advantage  in 
many  cases  where  the  clays  permit  mixing  and  where  they  are 
sufficiently  soft  to  be  easily  worked. 

Steam  Shovel. — The  steam  shovel  which  can  be  operated  at 
a  low  cost  when  constantly  in  service,  is  utilized  where  the  clay 
deposits  are  of  large  extent  and  where  they  are  of  sufficient  uni- 
formity in  composition  to  permit  mixing.  Steam  shovels  are  in 
common  use  in  working  the  clays  and  shales  of  Carboniferous 
age  in  Indiana,  Ohio  and  Pennsylvania. 

Open  Pit. — This  method  is  applicable  to  kaolinite  deposits 
that  are  in  the  form  of  veins.  Circular  pits  are  sunk  from  50  to 
75  feet  and  cribbed.  After  the  kaolinite  has  all  been  mined  out 

336 


CLAYS 


337 


Fig.  265. — Brick  yard,  kiln  and  drying  sheds,  St.  Johnsbury  Center, 
Vermont.     Photo,  by  C.  H.   Richardson. 


af 


Fig.    266. — Cretaceous    clay    bed,    Woodbridge ,    New    Jersey.     By 
courtesy  of  the  U.  S.  Geological  Survey. 


22 


338 


BUILDING    STONES   AND    CLAYS 


the  pit  is  filled  with  waste  and  the  cribbing  removed  as  the  filling 
proceeds.  A  second  pit  is  sunk  in  the  same  manner  and  the 
process  continued  until  the  entire  vein  of  kaolinite  has  been  mined 
out.  The  clay  is  raised  from  the  pit  in  buckets.  In  a  few  in- 
stances the  clay  is  so  sandy  that  it  has  to  be  washed.  In  such 
cases  it  can  be  agitated  with  water  in  the  pit  and  then  pumped 
to  the  clay  plant.  (See  Fig.  267.) 

Undermining. — In  come  cases  the  clay  deposit  is  undermined 
for  many  feet  along  the  floor  of  the  quarry.  A  series  of  wedges 
may  be  driven  into  the  clay  a  few  feet  above  the  quarry  floor  and 


Fig.  2G7. — Ball-clay  pit  at  Edgar,  Florida.     By  courtesy  of  the  U.  S. 
Geological  Survey. 

small  blocks  of  clay  broken  down.  Generally,  however,  the 
wedges  are  driven  into  the  clay  bed  from  the  top  of  the  forma- 
tion and  large  blocks  are  split  off  from  the  working  face  at  little 
expense.  These  blocks  are  broken  up  as  they  fall  on  the  quarry 
floor. 


UNDERGROUND  MINING 

Beds  of  clay  or  shale  are  often  overlain  with  many  feet  of  solid 
rock  whose  removal  would  be  exceedingly  expensive.     The  clay 


CLAYS  339 

or  shale  beds  may  or  may  not  appear  at  the  surface.  Their  edges 
or  ends  may  be  covered  with  talus  material  or  in  the  more  north- 
ern areas  with  glacial  debris.  The  position  of  the  beds  may  vary 
from  horizontal  to  vertical. 

Drifting. — This  method  is  applicable  where  the  edges  of  the 
clay  or  shale  bed  appear  at  the  surface  in  a  horizontal  position  or 
when  the  angle  of  slope  is  not  too  high.  Drifts  are  extended 
along  the  clay  bed  in  the  direction  of  the  strike.  Drifts  are  also 
made  upon  either  side  of  the  main  line  and  extended  outwards 
to  the  ends  or  edges  of  workable  clay  or  shale  deposits.  The  gen- 
eral appearance  of  this  branching  drift  is  quite  similar  to  the  vast 
network  of  drifts  seen  in  the  anthracite  coal  mines  of  Pennsyl- 
vania and  in  other  mines  elsewhere. 

A  modification  of  this  method  is  introduced  where  the  angle 
of  emergence  is  high.  It  is  perhaps  a  combination  of  the  shaft 
and  drift  method.  In  a  few  cases  the  beds  are  highly  folded  with 
the  interstratified  sedimentaries  or  tilted  to  an  angle  of  nearly 
90  degrees.  The  clay  is  removed  without  disturbing  the  inter- 
bedded  rocks. 

Shaft. — Where  clay  or  shale  beds  do  not  outcrop  at  the  sur- 
face a  shaft  is  sunk  until  the  clay  or  shale  is  encountered.  Drifts 
are  then  extended  in  various  directions  to  the  ends  and  edges  of 
the  workable  stratum  of  clay  or  shale.  The  material  mined  is 
raised  from  the  foot  of  the  shaft  as  ore  is  raised  from  a  mine.  It 
sometimes  happens  in  the  Carboniferous  clays  or  shales  that  there 
is  more  than  one  stratum  of  clay  and  more  than  one  bed  of  coal. 
In  such  cases  the  coal  is  mined  and  used  as  a  fuel  at  the  brick 
plant. 

Haulage. — The  simplest  known  method  of  transportation  of 
clay  to  the  plant  is  by  wheelbarrows.  This  method  is  still  ap- 
plicable where  the  tonnage  is  small  and  the  clay  beds  themselves 
are  in  close  proximity  to  the  brick  plant.  Where  the  tonnage 
becomes  considerable,  and  the  distance  of  the  clay  beds  from  the 
brick  plant  makes  the  former  method  impracticable,  carts  drawn 
by  mules  or  horses  have  been  introduced.  This  may  be  effected 
either  over  a  normal  road  or  a  temporary  railway.  Sometimes 
the  loaded  cars  are  run  to  the  plant  by  gravity  and  the  empties 
returned  by  mules.  Steam  haulage  is  applicable  where  the  clay 
beds  are  large,  the  distance  of  haulage  long  and  the  output  of  the 
factory  steady.  Aerial  tramways  have  been  introduced  in  some 
cases  to  transport  the  clay  or  shale  from  beds  at  the  higher  alti- 
tudes to  the  manufacturing  plant  at  the  lower  altitudes.  In  this 
case  the  loaded  bucket  returns  the  empty  one  to  the  mine. 


340  BUILDING    STONES   AND    CLAYS 

PREPARATION  OF  CLAY 

There  are  several  well  known  methods  of  preparing  clays  for 
mixing  and  molding.  Clays  are  frequently  so  impure  as  they 
come  from  the  mine  that  some  step  in  this  direction  becomes 
necessary. 

Crushing. — In  certain  cases  the  clays  as  they  come  from  the 
mine  are  crushed  so  as  to  reduce  all  pebbles  contained  in  the  clay 
as  well  as  the  clay  itself  to  an  impalpable  powder.  The  process 
does  not  necessitate  the  drying  of  the  clay.  Where  clays  are  not 
crushed,  screened  or  separated  in  any  manner  the  small  pebbles 
they  contain  often  render  the  exterior  of  brick  uneven  and  the 
output  of  the  plant  unsatisfactory. 

Screening. — -Screening  usually  necessitates  a  previous  drying 
of  the  clay.  Its  purpose  is  to  remove  all  pebbles  of  limestone, 
lumps  of  pyrite,  concretions  of  clay  iron  stones  and  all  other 
aggregations  of  matter  too  large  to  pass  through  the  screens.  If 
these  impurities  are  not  removed  their  effect  is  very  deleterious 
on  the  finished  product. 

Washing. — The  object  in  washing  clay  is  to  remove  the  sand 
and  pebbles  from  the  clay  before  mixing  and  molding.  The  fol- 
lowing methods  of  washing  are  taken  from  Bulletin  Number  35, 
New  York  State  Museum. 

Circular  Tubs. — In  this  process  the  clay  is  thrown  into  large 
circular  tubs  filled  with  water,  in  which  it  is  stirred  by  revolving 
arms  and  the  clay  lumps  thereby  disintegrated.  By  this  treat- 
ment the  fine  grains  of  kaolinite,  mica,  feldspar  and  quartz  re- 
main suspended  in  the  liquid,  while  the  coarser  grains  settle  to 
the  bottom  of  the  tank.  The  water  containing  the  suspended 
clay  is  drawn  off  into  settling  tanks. 

A  modification  of  this  process  consists  in  the  use  of  a  large 
cylinder  closed  at  both  ends.  It  is  set  in  a  horizontal  position  and 
contains  an  axis  with  iron  arms  whose  revolutions  break  up  the 
clay.  The  clay  is  fed  into  the  machine  through  a  hopper  at  the 
top.  A  current  of  water  passes  through  the  cylinder  and  carries 
away  the  finer  clay  particles  while  the  coarser  material  is  left  be- 
hind in  the  machine.  If  the  current  employed  is  too  slow  the  clay 
will  not  yield  a  sufficient  percentage  of  washed  product.  If  the 
current  is  too  rapid  some  of  the  coarse  material  will  be  washed 
out  of  the  cylinder.  The  chief  objection  to  this  method  is  that 
the  apparatus  has  to  be  stopped  from  time  to  time  to  remove  the 
coarse  sand  and  pebbles  from  the  machine. 

Log  Washing. — The  apparatus  consists  of  a  semicylindrical 
trough  in  which  revolves  a  horizontal  axis  with  short  arms.  The 


CLAYS  341 

arms  break  up  the  kaolin  more  or  less  according  to  its  density  and 
facilitate  the  subsequent  washing.  The  stream  of  water  directed 
into  the  log  washer  sweeps  the  kaolin  and  most  of  the  sand  into 
the  washing  trough.  This  trough  is  about  15  inches  wide  and  12 
inches  deep,  but  should  be  wider  and  deeper  if  the  clay  is  very 
sandy. 

The  washing  trough  has  a  pitch  of  1  inch  in  20  feet,  but  the 
amount  of  pitch  should  depend  on  the  kaolin  and  whether  the 
contained  sand  is  fine  or  coarse.  The  finer  the  kaolin  the  more 
slowly  it  will  settle  and  the  lower  will  be  the  pitch  of  the  trough. 
The  water  is  conducted  from  the  trough  into  settling  vats.  As  a 
further  and  necessary  precaution  it  is  discharged  on  a  100  mesh 
screen  to  remove  any  coarser  particles  that  might  remain  together 
with  all  bits  of  wood  and  floating  dirt. 

Stationary  Screens.  —  The  stationary  screen  consists  of  a 
frame  covered  with  copper  cloth  and  set  at  a  slight  angle.  The 
water  and  suspended  kaolin  pass  through  the  screen.  Sometimes 
two,  or  three  screens  which  overlap  each  other  are  used  so  that 
whatever  kaolin  does  not  fall  through  the  first  may  be  caught 
later  on  the  other  screens.  Stationary  screens  are  likely  to  clog 
with  vegetable  matter  and  pieces  of  wood  and  therefore  must  be 
closely  watched. 

Revolving  Screens.  —  Revolving  screens  are  the  most  satis- 
factory, for  they  are  self -cleansing.  They  are  barrel-shaped  and 
the  water  with  the  suspended  clay  is  charged  into  the  interior  and 
passes  outward  through  the  screen  cloth.  As  the  screen  revolves 
the  dirt  is  carried  upward  and  dropped  on  a  board  which  diverts 
it  to  the  ground. 

Settling  Tank. — The  settling  tank  into  which  the  water  and 
suspended  kaolin  falls  is  usually  about  50  feet  long,  8  feet  wide 
and  4  feet  deep.  As  soon  as  one  is  filled  the  water  is  diverted 
into  another.  The  larger  the  tanks  the  more  uniform  will  be  the 
marketable  product.  If  the  kaolin  settles  too  slowly  a  little  alum 
is  sometimes  added  to  the  water  to  hasten  the  deposition.  When 
the  kaolin  has  settled  most  of  the  clear  water  is  drawn  off.  The 
creamlike  mass  of  kaolin  and  water  in  the  bottom  of  the  vat  is 
drawn  off  by  means  of  slip  pumps  and  forced  by  these  into  the 
presses. 

Presses. — The  presses  consist  of  flat  iron  or  wooden  frames 
between  which  are  flat  canvas  bags.  These  bags  are  connected 
by  ripples  with  a  supply  tube  from  the  slip  pumps,  and  by  means 
of  pressure  from  the  pumps  nearly  all  of  the  water  is  forced  out 
of  the  kaolin  through  the  canvas.  When  as  much  water  as  pos- 
sible is  squeezed  out  the  press  is  opened  and  the  sheets  of  semi- 


342  BUILDING    STONES   AND    CLAYS 

dry  kaolin  are  taken  out.  The  product  is  then  dried  either  on 
racks  in  the  open  air  or  in  a  steam  heated  room. 

Yield. — Every  ton  of  crude  kaolin  should  yield  from  one- 
fourth  to  two-fifths  of  a  ton  of  washed  kaolin.  The  washing  plant 
should  be  located  if  possible  at  the  mines  to  avoid  the  transporta- 
tion of  60  or  70  per  cent  of  waste  sand  which  has  to  be  washed 
out  before  the  kaolin  can  be  used  or  placed  on  the  market. 

Cyclonic  Separation. — This  process  consists  of  feeding  the 
clay  in  a  dry  state  into  a  pulverizer  which  reduces  the  kaolin  to  a 
powder.  The  material  is  discharged  from  the  pulverizer  into  a 
box  or  tunnel  and  the  finer  particles  are  carried  upward  by 
cyclonic  currents  of  air  to  the  end  of  the  airway,  where  they  are 
dropped  into  storage  bins.  The  heavier  particles  fall  back  into 
the  crusher.  The  method  is  applicable  to  kaolins  that  are  free 
from  pyrite  and  siderite  or  clay  iron  concretions. 

EMPLOYMENT  OF  CLAYS 

Value. — Most  clays  are  manufactured  into  clay  products  by 
corporations  or  individuals  directly  concerned  in  mining  them. 
Some  kaolins,  fire  clays,  ball  clays,  paper  clays,  pottery  clays  and 
terra  cotta  are  sold  by  the  ton  either  f.  o.  b.  or  at  the  market. 
The  price  ranges  from  50  cents  a  ton  for  some  pottery  clays  to 
$12  per  ton  for  washed  kaolins.  The  price  of  fire  clays  varies 
from  $1  to  $2  per  ton.  Paper  clays  vary  from  $7  to  $10  per  ton. 

In  the  examination  and  estimation  of  the  value  of  any  clay 
deposit  not  only  must  all  of  the  physical  and  chemical  charac- 
teristics be  called  into  question  but  also  the  structure  and  mode 
of  occurrence  must  be  considered.  It  is  also  necessary  to  work 
out  by  means  of  the  clay  auger  the  tonnage  of  the  deposit  and 
determine  the  market  value  for  that  particular  kind  of  clay. 

Uses. — The  following  summation  of  uses  was  worked  out  by 
R.  T.  Hill  for  the  Mineral  Resources  of  the  United  States  in 
1891  and  modified  by  H.  Ries  in  his  Professional  Paper  Number 
11,  U.  S.  Geological  Survey. 

Domestic. — Porcelain,  white  earthen  ware,  stone  ware,  yellow 
ware  and  Rockingham  ware  for  table  service  and  cooking ;  ma- 
jolica stoves ;  polishing  brick,  bath  brick  and  fire  kindlers. 

Structural. — Brick;  common,  front,  pressed,  ornamental,  hol- 
low, glazed,  adobe,  terra  cotta ;  roofing  tile ;  glazed  and  encaustic 
tile  ;  drain  tile  ;  paving  brick ;  chimney  flues  ;  chimney  pots  ;  door- 
knobs ;  fireproofing ;  terra  cotta  lumber ;  copings ;  fence  posts. 

Hygienic. — Urinals,  closet  bowls,  sinks,  washtubs,  bathtubs, 
pitchers,  sewer  pipe,  ventilating  flues,  foundation  blocks,  vitri- 
fied brick. 


CLAYS  343 

Decorative. — Ornamental  pottery,  terra  cotta,  majolica,  gar- 
den furniture,  tombstones. 

Minor  Uses. — Food  adulterant,  paint  fillers,  paper  filling,  elec- 
tric insulators,  pumps,  fulling  cloth,  scouring  soap,  packing  for 
horses'  feet,  chemical  apparatus,  condensing  worms,  ink  bottles, 
ultramarine  manufacture,  emery  wheels ;  playing  marbles ;  bat- 
tery cups ;  pins,  stilts  and  spurs  for  potter's  use ;  shuttle  eyes 
and  thread  guides ;  smoking  pipes ;  umbrella  stands ;  pedestals ; 
filter  tubes ;  caster  wheels ;  pump  wheels. 

Refractory  Wares. — Crucibles  and  other  assaying  apparatus ; 
gas  retorts ;  fire  bricks ;  glass  pots ;  blocks  for  tank  furnaces ; 
saggers  ;  stove  and  furnace  bricks  ;  blocks  for  fire  boxes ;  tuyeres ; 
cupola  bricks. 

Engineering  Works. — Puddle;  Portland  cement;  railroad  bal- 
last; wrater  conduits;  turbine  wheels. 

According  to  Jefferson  Middleton  in  the  report  of  the  clay 
working  industry  of  the  United  States  for  1914  the  value  of  the 
clay  products  for  that  year  in  the  United  States  was  $164,986,983. 
Brick  and  tile  represent  a  value  of  $129,588,822,  and  pottery 
$35,398,161.  The  average  annual  value  of  clay  products  from 
1910  to  1914  was  $170,287,909.  In  1914  clay  products  were 
manufactured  in  every  state.  The  territories,  Alaska  and 
Hawaii,  reported  no  production. 

Ohio  has  maintained  the  rank  of  the  leading  producer  ever 
since  figures  were  first  compiled  by  the  Geological  Survey  in 
1894.  The  production  in  Ohio  in  1914  was  valued  at  $37,166,768. 
Pennsylvania's  output  was  valued  at  $21,946,996.  New  Jersey, 
$16,484,652.  Illinois,  $13,318,953.  New  York,  $9,078,933. 

For  a  more  complete  description  of  clays  see  the  important 
publications  of  Prof.  H.  Ries  as  listed  in  the  references  on 
page  344. 


344  BUILDING    STONES   AND    CLAYS 

REFERENCES 

Baker,  Ira  O.,  A  treatise  on  Masonry  Construction ;  John  Wiley 
and  Sons,  New  York,  1913. 

Bleininger,  A.  V.  The  Effect  of  Heat  upon  Clays ;  T.  A.  Ran- 
dall and  Co.,  Indianapolis,  Indiana. 

Crossley,  A.  Tables  of  Analyses  of  Clays;  T.  A.  Randall  and 
Co.,  Indianapolis,  Indiana. 

Eckel,  E.  C.  Building  Stones  and  Clays ;  John  Wiley  and  Sons, 
New  York,  1912. 

Griffen,  H.  R.  Clay  Glazes  and  Enamels  ;  T.  A.  Randall  and 
Co.,  Indianapolis,  Indiana. 

Richardson,  N.  D.  Kiln  Records;  T.  A.  Randall  and  Co.,  In- 
dianapolis, Indiana. 

Ries,  H.  The  Clays  of  the  United  States  East  of  the  Mississippi 
River;  U.  S.  Geol.  Survey,  Professional  Paper  No.  11,  1903. 

Ries,  H.  Clays :  Their  Occurrence,  Properties  and  Uses  ;  John 
Wiley  and  Sons,  New  York,  1908. 

Ries,  H.  Building  Stones  and  Clay  Products ;  John  Wiley  and 
Sons,  New  York,  1912. 

Ries,  H.,  and  Henry  Leighton,  History  of  the  Clay-Working 
Industry  in  the  United  States ;  John  Wiley  and  Sons,  New 
York,  1913. 


CHAPTER  X 

BUILDING  BRICK 

Common  Brick. — The  ordinary  clays  and  shales  are  used  in 
the  manufacture  of  common  brick.  Whatever  the  color  of  the 
original  clays  may  have  been  the  most  of  the  brick  burn  red. 
Many  of  the  clays  of  Illinois,  Michigan  and  Wisconsin  burn  to 
a  creamy  white  product  because  the  clays  are  rich  in  lime.  The 
drab  and  bluish  glacial  and  terrace  clays  of  New  England  have 
given  rise  to  many  brick  homes  that  are  fairly  permanent.  The 
brick  are  often  manufactured  near  the  site  where  the  house  is 
erected.  Fig.  268  represents  a  house  built  from  glacial  clays 
in  Calais,  Vermont,  in  1815.  (See  Fig.  268.) 

The  requisites  for  common  clays  are  that  they  shall  mold 
easily  and  burn  to  a  hard  product  at  comparatively  low  tempera- 
tures. 

Pressed  Brick. — These  are  usually  manufactured  from  the 
higher  grade  clays.  The  clays  may  be  classified  according  to 
the  color  of  the  burned  products.  (1)  Red-burning  clays. 
(2)  Buff-burning  clays.  (3)  White-burning  clays. 

The  requisites  for  pressed  brick  clays  are  as  follows:  (1)  The 
clays  must  burn  to  a  fairly  uniform  color.  There  is  a  consider- 
able deviation  from  this  demand  at  the  present  time.  (2)  Free- 
dom from  warping  and  splitting.  (3)  Absence  of  soluble  salts 
in  the  clays.  (4)  The  burned  product  must  be  sufficiently  hard 
for  structural  purposes.  (5)  The  absorption  of  the  finished  pro- 
duct must  be  low.  (See  Fig.  269.) 

Enameled  Brick. — The  clays  used  in  the  manufacture  of  buff 
pressed  brick  are  well  adapted  for  the  manufacture  of  enameled 
brick.  As  the  name  implies  the  brick  is  covered  with  an  enamel 
which  conforms  to  the  clay  body  to  prevent  scaling  or  cracking. 

Fire  Brick. — Fire  brick  are  manufactured  from  nearly  pure 
clays,  or  from  pure  clay  and  clean  sand,  or  from  nearly  pure 
silica  cemented  with  a  small  amount  of  clay.  Clays  designed 
for  the  manufacture  of  fire  brick  must  contain  less  than  6  per 
cent  of  the  oxides  of  iron  and  less  than  3  per  cent  of  combined 
calcium,  magnesium,  sodium  and  potassium  minerals.  Pyrite  is 
perhaps  the  most  objectionable  mineral  ever  present  in  fire  clays. 

Fire  brick  are  designed  for  use  whenever  high  temperatures 
are  to  be  resisted.  Such  brick  should  be  uniform  in  size,  regular 

345 


346 


BUILDING    STONES   AND    CLAYS 


m 


F'ig.  268. — Brick  house  built  in  Calais,  Vermont,  in  1815,  with  brick 
manufactured  from  glacial  clays.      Photo,  by  C.  H.  Richardson. 


Fig.  269. — Castle  of  St.  Angelo,  Rome,  Italy,  built  of  brick  in  62 
B.  C.  In  the  foreground  is  the  famous  brick  bridge  Pons  Fabricius, 
which  has  withstood  floods,  earthquakes  and  conflagrations  all  the 
intervening  centuries.  By  courtesy  of  T.  A.  Randall  and  Company,. 


BUILDING    BRICK 


347 


in  shape,  homogeneous  in  texture,  uniform  in  composition,  easily 
cut,  strong  and  infusible. 

Molding. — The  slow  and  laborious  method  of  pressing  plastic 
clays  by  hand  into  various  molds  is  now  supplemented  by  a  great 
variety  of  machines  for  preparing  and  molding  the  clays.  (1) 
The  soft-mud  machine.  The  clay  is  reduced  to  a  soft  mud  by 
adding  about  one  quarter  of  its  volume  of  water.  (2)  Stiff-mud 
machines.  For  this  machine  the  clay  is  formed  into  a  stiff  mud. 
(3)  Dry-clay  machines.  Here  the  dry  clay,  or  clay  that  is  nearly 
dry,  is  forced  into  the  mold  by  heavy  pressure  without  the 


Fig.  270. — Immense  strip  bank  of  the  Clay  Products  Company, 
Brazil,  Indiana.  By  courtesy  of  T.  A.  Randall  and  Company. 

reduction  of  the  clay  to  a  plastic  state.  In  the  filling  of  the 
molds  there  is  sometimes  a  continuous  stream  of  clay  forced 
from  the  pug  mill  through  a  die  and  afterwards  cut  up  into 
bricks.  Again  the  clay  is  forced  into  molds  moving  under  the 
nozzle  of  the  pug-mill. 

Burning. — The  length  of  time  that  brick  should  be  burned 
varies  with  the  character  of  the  clay,  the  form  and  size  of  the 
kilns,  and  the  kind  of  fuel  used.  In  the  older  process  of  burning, 
the  brick  when  dry  enough  to  handle  are  built  up  in  arches.  The 
eye  of  the  arch  runs  through  the  entire  kiln  and  in  this  the  fuel 
for  burning  the  bricks  is  placed.  The  whole  stack  is  then  covered 


348  BUILDING    STONES    AND    CLAYS 

with  a  wall  of  green  brick  and  all  openings  carefully  plastered 
up  with  mud.  The  drying  and  burning  takes  from  6  to  15  days. 
The  kiln  is  at  first  subjected  to  only  a  moderate  heat  but  after 
the  moisture  has  been  expelled  the  heat  is  increased  slowly  until 
the  bricks  next  to  the  eye  of  the  kiln  attain  a  white  heat.  The 
temperature  is  then  kept  nearly  at  a  constant  until  the  burning 
is  complete.  All  openings  are  then  closed  and  the  mass  allowed 
to  cool  slowly.  (See  Fig.  270.) 

In  the  modern  practice  of  burning  the  brick  the  principal 
yards  have  permanent  kilns.  Rectangular  spaces  are  surrounded, 
save  for  very  wide  doors  at  the  ends,  by  permanent  brick  walls 
which  have  fire  boxes  on  the  outside.  The  circular  kilns  are 
entirely  enclosed  with  brick  masonry.  They  are  sometimes  made 
in  separate  compartments,  each  of  which  has  a  separate  entrance 
and  an  independent  connection  with  the  chimney.  The  latter 
may  be  built  within  the  kiln  or  entirely  outside  the  kiln.  In 
either  case  a  downward  draught  is  secured.  Fine  coal  is  placed 
near  the  top  of  the  kiln  and  the  down  draught  causes  a  free 
circulation  of  the  flame  and  the  heated  gases  about  the  material 
being  burned.  The  advantages  of  compartment  kilns  are  that 
while  some  are  being  burned  others  may  be  filled  and  still  others 
emptied.  In  Texas  crude  oil  is  often  the  fuel  used. 

Water  Smoking. — In  water  smoking  the  fire  of  the  kiln  is 
raised  slowly  and  gradually  to  temperatures  not  exceeding  200 
degrees  C.  The  object  of  slowly  expelling  this  hygroscopic 
moisture  is  to  prevent  the  fracture  of  the  brick  by  the  rapid 
expansion  of  steam.  Steam  pressure  may  be  sufficient  to  loosen 
the  bond  of  clay  or  produce  fissures  along  the  laminations.  When 
such  brick  are  struck  with  a  hammer  they  sound  dead  like  a 
fractured  stone.  The  point  when  all  the  hygroscopic  moisture 
has  been  driven  off  may  be  determined  by  thrusting  a  cold  rod 
into  the  kiln  flue.  If  the  rod  is  moist  upon  withdrawal  steam  is 
still  coming  off  from  the  clay  products.  If  the  rod  is  dry  the 
process  of  water  smoking  is  complete. 

Dehydration  and  Oxidation. — These  two  steps  in  the  burning 
of  clay  products  overlap  each  other  and  are  therefore  carried 
on  simultaneously.  The  former  requires  the  expenditure  of 
heat  while  the  latter  produces  heat.  In  dehydration  the  chemi- 
cally combined  water  must  be  expelled  from  the  brick  and  also 
the  carbon  dioxide  of  the  carbonates  driven  out  of  the  various 
wares.  In  oxidation  the  carbon  and  the  sulphides  must  be  burned 
out  and  the  ferrous  iron  oxidized  to  the  ferric  condition. 

One  method  for  determining  the  progress  of  dehydration 
is  to  remove  a  brick  from  time  to  time  and  weigh  it.  As  long 


BUILDING    BRICK 


349 


as  the  brick  continues  to  lose  weight  the  process  of  dehydration 
is  incomplete.  The  proper  practical  dehydration  temperature 
is  not  less  than  650  degrees  C.  Pyrometers  are  now  in  general 
use  in  the  brick  industry. 

The  expulsion  of  the  carbonic  acid  in  the  carbonates  of  lime 
and  iron  extends  over  a  longer  period  of  time.  The  two  are 
expelled  at  approximately  the  same  time.  After  the  carbon 
dioxide  has  been  expelled  from  the  limestone  grains  the  re- 
maining lime  is  ready  to  serve  as  a  fluxing  agent.  The  iron 


m  n  mn 

f  -i  -i 


Fig.  271. — Setting  a  kiln  of  rough  X  brown  brick.  By  courtesy  of 
T.  A.  Randall  and  Company. 

at  the  same  time  is  in  the  ferrous  condition  and  ready  for  oxida- 
tion. According  to  A.  V.  Bleininger  the  most  favorable  tempera- 
ture for  oxidation  is  750  degrees  C.  And  according  to  E.  Orton 
800  degrees  C.  The  time  required  for  complete  oxidation  varies 
from  4  to  7  days.  (See  Fig.  271.) 

Vitrification. — This  part  of  the  process  as  the  name  implies 
leads  to  the  formation  of  a  glassy  product,  or  tends  to  fuse 
the  clay  into  a  glass.  The  work  begins  during  the  last  stages 
of  oxidation  and  immediately  thereafter.  The  first  result  is  a 


350  BUILDING    STONES    AND    CLAYS 

consolidation  and  hardening  of  the  clay.  Several  different  stages 
are  noted  in  the  process.  (1)  Earthen  fracture  stage.  This  is 
the  one  usually  observed  in  common  building  brick.  There  is 
no  glassiness  observed  and  the  color  of  the  brick  is  a  light  red. 
(2)  Incipient  vitrification.  The  color  of  the  brick  is  now  a  darker 
red.  The  crushing  strength  is  raised  from  about  4,500  Ib.  per 
square  inch  to  about  8,000.  Burning  is  insufficient  to  permit  the 
material  to  be  used  for  paving  purposes.  (3)  Dense  vitrification. 
Here  the  pores  are  largely  closed.  The  color  is  a  dark  chocolate 
brown.  For  many  clays  the  maximum  toughness  is  here  reached. 
The  fracture  shows  a  dense,  compact,  but  not  a  glassy  surface. 
(-i)  Viscous  vitrification.  In  this  stage  the  ware  becomes  vesi- 
cular, sometimes  deformed,  while  often  it  shows  distinct  kiln 


Fig.  272. — Panoramic  view  of  the  stock  yards  of  the  Clay  Products 
Company's  plant,  Brazil,  Indiana.  By  courtesy  of  T.  A.  Randall  and 
Company. 

marks.  (5)  Fusion.  This  is  the  final  step  in  complete  vitrifi- 
cation. 

Coloration. — According  to  H.  A.  Segar  clays  high  in  iron 
oxide,  low  in  alumina  and  free  from  lime  burn  red  in  oxidizing 
gases.  Clays  high  in  iron  oxides  and  lime  but  low  in  alumina  burn 
buff.  Clays  fairly  high  in  alumina  but  with  about  3  per  cent  of 
iron  oxide  content  burn  buff.  Clays  high  in  alumina  and  low  in 
iron  burn  to  a  white  or  light  buff  color.  The  colors  actually 
imparted  to  clay  products  depend  upon  both  the  chemical  com- 
position of  the  clay  itself  and  upon  the  character  of  the  burning. 
Red  burning  always  may  be  made  to  assume'  a  black  color  by 
causing  reducing  conditions  to  prevail  during  the  first  stages 
of  the  burning.  (See  Fig.  272.) 

Artificial  Brick  Colors. — With  the  exception  of  wall  and  floor 
tiles  and  some  classes  of  terra  cotta  the  various  oxides  of  iron 
and  manganese  are  used.  Limonite  may  be  mixed  with  the 


BUILDING    BRICK 


351 


original  clay  to  produce  the  darker  hues.  Hematite  has  been 
added  to  produce  the  dark  specks  desired  in  flashed  brick.  Pyro- 
lusite  in  the  granular  form  is  often  added  to  give  this  effect. 

A  white  coloration  is  produced  by  a  mixture  of  white  burning 
clays.  A  gray  color  by  the  use  of  small  quantities  of  manganese 
pulp.  Black  is  produced  by  a  mixture  of  iron  and  manganese 
oxides  with  a  small  amount  of  cobalt  oxide.  A  red  color  is 
obtained  by  burning  a  good  clay  rich  in  iron  oxides.  Buff  and 
yellow  colors  may  be  produced  by  mixing  lime  with  clays  bear- 
ing iron.  A  bro\vn  color  is  obtained  by  burning  a  red  burning 


~1 


Fig.  273. — Post  Office,  Bradford,  Pennsylvania,  built  of  brick,  Oscar 
Wenderoth,  architect.  By  courtesy  of  T.  A.  Randall  and  Company. 

clay  with  manganese  and  chrome  oxides.  Green  colors  are  pro- 
duced by  the  use  of  chrome  oxide.  A  blue  color  can  be  obtained 
with  small  quantities  of  cobalt  oxide. 

Classification  of  Building  Brick. — Building  bricks  are  classi- 
fied according  to  (1)  The  way  in  which  they  are  molded.  (2) 
Their  position  in  the  kiln  while  being  burned.  (3)  Their  form 
or  use.  (See  Fig.  273.) 

Classification  According  to  Method  of  Molding.  —  Ira  O. 
Baker  in  his  Treatise  on  Masonry  Construction  gives  the  follow- 
ing classification : 


352 


BUILDING    STONES   AND    CLAYS 


Soft-mud  Brick. — A  brick  made  by  placing  soft  clay  in  a  mold. 
It  may  be  molded  either  by  hand  or  by  machinery. 

Stiff-mud  Brick. — One  molded  by  forcing  a  prism  of  stiff  clay 
through  a  die  and  afterwards  cutting  it  up  into  bricks. 

Pressed  Brick. — Usually  a  stiff-mud  brick  which  has  been  sub- 
jected to  a  great  pressure  to  render  the  form  more  regular  and 
to  increase  its  strength  and  density.  A  soft-mud  brick  after  being 
partially  dried  may  be  re-pressed  to  improve  its  form  and  increase 
its  strength  and  density. 


i 


Fig.  274.— Clay  bank  14  feet  deep,  Bridgeton,  New  Jersey.  By 
courtesy  of  W.  W.  Ridgely. 

Slop  Brick.— A  brick  made  by  hand  with  the  molds  dipped  in 
water  before  filling  the  mold  with  clay.  This  is  done  to  prevent 
the  clay  from  sticking. 

Sanded  Brick.— Brick  made  by  the  soft-mud  process  where 
sand  is  sprinkled  into  the  molds  to  prevent  the  clay  from  sticking. 

Machine-made  Brick. — The  use  of  this  term  now  is  indefinite 
for  practically  all  grades  and  kinds  of  brick  are  made  by  ma- 
chinery. 

Classification  According  to  Position  in  Kiln. — Where  brick 
are  burned  in  up-draught  kilns  this  classification  becomes  impor- 


BUILDING    BRICK 


353 


tant.  With  the  new  style  of  kilns  and  improved  methods  of  burn- 
ing, the  quality  is  so  nearly  uniform  throughout  the  entire  kiln 
that  the  classification  loses  its  significance. 

Arch,  or  Clinker  Bricks. — These  brick  form  the  top  and  sides 
of  the  arches  in  which  the  brick  are  burned.  They  are  hard, 
brittle  and  weak. 

Body,  Cherry,  or  Hard  Bricks. — These  are  taken  from  the 
interior  of  the  kiln.  They  are  the  best  brick  of  the  entire  burn. 

Salmon,  Pale,  or  Soft  Bricks. — Those  which  form  the  exterior 


Fig.  275. — General  view  of  brick  yard,  Bridgeton,  New  Jersey.  By 
courtesy  of  W.  W.  Ridgeley. 

of  the  mass.  They  are  under  burned  and  too  soft  for  ordinary 
use,  save  for  filling.  The  terms  salmon  and  pale  refer  to  the 
color  of  the  brick.  There  is  no  relation  between  color  and 
strength  and  density. 

Classification  According  to  Use. — The  form  and  use  of  bricks 
gives  rise  to  several  different  terms. 

Compass  Brick. — A  brick  having  one  edge  shorter  then  the 
other.  Such  brick  are  used  in  lining  circular  shafts,  etc. 

Feather-edge  Brick. — Such  bricks  have  one  edge  thinner  than 
23 


354 


BUILDING    STONES   AND    CLAYS 


the  other.  They  are  used  in  arches  and  often  called  voussoir 
brick. 

Face  Brick. — This  term  is  usually  applied  to  re-pressed  brick 
possessing  uniformity  of  size  and  color.  They  are  used  in  the 
face  of  the  walls  of  buildings.  (See  Figs.  274,  275,  276,  277,  278, 
279  and  280.) 

Sezvcr  Brick. — These  are  the  smooth,  regular  and  ordinary 
hard  brick. 

Paving  Brick. — A  vitrified  clay  block  which  is  very  hard  and 
somewhat  larger  than  ordinary  building  brick.  The  term  brick 
paving-block  is  in  common  use. 


Fig.  276. — Machine  room,  Bridgeton  brick  works,  Bridgeton,  New 
Jersey.  By  courtesy  of  W.  W.  Ridgely. 

Vitrified  Brick. — Such  brick  are  burned  to  the  point  of  vitrifica- 
tion and  then  annealed  or  toughened  by  slowly  cooling.  They 
were  originally  manufactured  for  paving  purposes  but  now  they 
are  much  used  in  building  and  engineering  structures. 

Tests  for  Building  Brick. — Five  tests  are  frequently  applied 
to  determine  the  quality  of  building  brick.  (1)  Form.  (2)  Tex- 
ture. (3)  Absorptive  power.  (4)  Resistance  to  compression. 
(5)  Transverse  strength. 

Form. — The  regularity  of  form  usually  depends  upon  the  qual- 
ity of  the  clay  used  and  the  method  of  burning  the  finished 


BUILDING    BRICK 


355 


product.  Building  brick  should  have  plane  surfaces,  parallel 
sides,  sharp  edges  and  angles.  In  regularity  of  form  re-pressed 
brick  stands  first ;  dry-clay  brick,  second ;  stiff-mud  brick,  third ; 
and  soft-mud  brick,  fourth. 

Texture. — Good  building  brick  should  have  a  fine,  compact  and 
uniform  texture.  They  should  contain  no  fissures,  sand  seams, 
air  bubbles,  pebbles  of  any  kind,  or  lumps  of  lime.  They  should 
give  a  clear  ring  when  struck  with  a  hammer.  A  dull  dead  sound 
suggests  a  flaw  or  fracture. 

The  relative  value  of  any  brick  depends  largely  upon  the 
character  of  the  clay  used  in  its  manufacture  and  its  compactness 


Fig.  277. — Loaded  kiln,  Erickson's  brick  yards,  Bridgeton,  New 
Jersey.  Photo,  by  H.  K.  MacPherson. 

upon  the  method  of  molding.  In  compactness  and  uniformity  of 
texture  hand-molded  brick  stands  first ;  machine-molded,  soft- 
mud  brick,  second ;  machine-molded  stiff-mud  brick,  third ;  and 
dry-clay  brick,  fourth. 

Absorptive  Power. — The  absorptive  power  of  building  brick 
varies  with  the  chemical  composition  of  the  clay  used  in  the 
manufacture  of  the  brick.  There  seems  to  be  no  close  relation 
between  the  absorptive  power  and  the  strength  of  brick,  or  the 
loss  of  strength  by  freezing.  Some  vitrified  brick  will  absorb 
only  from  1  to  2  per  cent  of  water.  Some  dry-clay  or  pressed 
brick  will  absorb  only  from  5  to  10  per  cent  of  water,  while 


356  BUILDING    STONES   AND    CLAYS 

others  will  absorb   from  130  to  35  per  cent  of  their  weight  of 
water. 

Compressive  Strength. — The  crushing  strength  of  building 
brick  is  of  far  less  importance  than  that  of  building  stones.  The 
brick  are  of  much  smaller  dimensions  than  the  stone  used  for 
structural  purposes,  the  percentage  of  mortar  is  relatively  higher, 
therefore,  the  strength  of  brick  masonry  depends  largely  upon  the 
kind  of  mortar  used  in  laying  the  brick. 

The  compressive  strength  of  brick  sent  to  the  World's  Colum- 
bian Exposition  is  given  in  Tests  of  Metals,  etc.,  1894,  pp.  456- 
468.  The  highest  compressive  strength  in  pounds  per  square 
inch  is  here  given,  together  with  the  state  or  country  where  the 
brick  were  manufactured. 

Lb.  per  Sq.  In. 

Arkansas    9,469 

Florida    5,077 

Idaho 22,561 

Illinois 12,280 

Iowa    12,269 

Minnesota 7,402 

S.  Dakota 8,936 

Utah    4,362 

Washington    13,137 

Wyoming    13,077 

Japan    5,529 

Sweden   22,955 

Brick  Building  in  1914. — The  United  States  Geological  Sur- 
vey is  now  striving  to  compile  statistics  that  will  annually  show 
the  relative  progress  in  building  operations  in  the  chief  cities  of 
the  United  States. 

According  to  figures  already  compiled  the  value  of  the  new 
buildings  in  113  cities  for  1914  was  $461,681,108.  The  value  of 
the  fire  resisting  buildings  was  $296,454,858.  The  value  of  brick 
buildings  was  $181,957,682.  The  value  of  wooden  buildings  was 
$165,226,250.  Other  fire  resisting  buildings  than  brick  repre- 
sented a  value  of  $114,497,176. 

These  figures  show  that  brick  leads  all  other  materials  used  for 
building  purposes  in  these  cities  and  that  the  total  of  new  brick 
buildings  exceeds  the  combined  total  of  wooden  buildings  and 
fire  resisting  buildings  other  than  brick.  The  advantages  of 
building  with  brick  may  be  tersely  characterized  as  safety, 
economy,  stability,  comfort,  beauty  and  satisfaction. 


BUILDING    BRICK 


357 


BRICK  AND  TILE  PRODUCTION  FOR  1915 

According  to  Jefferson  Middleton  the  total  value  of  clay 
products  marketed  for  1915  was  $163,120,232,  as  compared  with 
$163,986,983  in  1914.  The  most  prominent  features  in  the  indus- 
tries may  be  tabulated  as  follows:  (1)  The  large  increase  in 
production  and  the  even  larger  increase  in  value  of  common  brick 
in  Cook  County,  Illinois,  where  the  production  was  739,173,000 
brick.  This  region  now  becomes  the  rival  of  the  New  York 


Fig.  273. — Burned  brick  at  storage  sheds,  Bridgeton  brick  works, 
Bridgeton,  New  Jersey.  Photo,  furnished  by  the  Bridgeton  Brick 
Company. 

portion  of  the  Hudson  River  region.  (2)  The  large  increase  in 
the  production  and  value  of  fire  brick.  (3)  The  increase  in  value 
of  front  brick.  (4)  The  large  increase  in  value  of  clay  products 
in  Illinois  and  Pennsylvania.  (5)  The  large  decrease  in  value  of 
sewer  pipe.  (6)  The  small  increase  in  average  price  per  thou- 
sand of  common  brick  and  the  decrease  in  average  price  of  other 
varieties  of  brick. 

Common  brick,  as  its  name  implies,  is  the  most  widelv  dis- 


358 


BUILDING    STONES   AND    CLAYS 


tributed  of  the  clay  products,  being  reported  from  every  State 
and  Territory  except  Alaska  and  Hawaii.  Illinois  was  the  largest 
producer  of  common  brick  in  1915  with  a  value  of  $6,870,990. 
This  state  was  followed  by  New  York,  Pennsylvania,  Ohio  and 
New  Jersey  in  the  order  named. 

Fire  brick  ranks  second  amongst  the  brick  and  tile  products. 
It  was  reported  from  35  states  in  1915.  Pennsylvania  ranked 
first  with  a  value  of  $7,177,629,  followed  by  Ohio,  Missouri  and 
Kentucky  in  the  order  named. 

Vitrified  brick  or  block,  the  third  brick  and  tile  product  in 
value  in  1915,  was  reported  from  31  states.  Ohio  ranked  first 


/illlrF 


Fig.  279. — Armory,  Bridgeton,  New  Jersey,  built  of  Bridgeton  brick. 
Photo,  furnished  by  the  Bridgeton  Brick  Company. 

with  a  value  of  $4,017,738,  followed  by  Illinois  and  Pennsylvania 
in  the  order  named. 

Front  or  face  brick  is  widely  distributed,  sales  being  reported 
from  42  states  in  1915.  Pennsylvania  ranked  first  with  an  output 
valued  at  $2,631,795  followed  by  Ohio,  Indiana  and  Illinois  in 
the  order  named. 

Draintile  was  reported  from  36  states.  Iowa  ranked  first  with 
a  value  of  $3,802,599,  followed  by  Ohio,  Indiana  and  Illinois  in 
the  order  named. 

Sewer  pipe  was  reported  from  27  states.     Ohio  ranked  first 


BUILDING    BRICK 


359 


with  an  output  of  $3,719,790,  followed  by  Missouri,  Pennsylvania 
and  California  in  the  order  named. 

Fireproofing,  including  hollow  building  tile  or  block,  was  re- 
ported from  35  states.  Ohio  ranked  first  with  a  value  of 
$2,172,701,  followed  by  New  Jersey  and  Iowa  in  the  order  named. 

Architectural  terra  cotta  was  reported  from  12  states  in  1915. 
New  Jersey  ranked  first  with  an  output  valued  at  $1,430,968, 
followed  by  Illinois  and  New  York  in  the  order  named. 

The  rank  of  the  first  ten  states,  the  value  of  the  output  and  the 
percentage  of  the  total  value  of  clay  products  may  be  tabulated 
for  1915  as  follows: 


Post  Office,   Bridgeton,   N.'j. 


Fig.   280. — Post   Office,   Bridgeton,   New  Jersey,  built  of   Bridgeton 
brick.     Photo,  furnished  by  B.  W.  Roberts. 


Rank.  Value. 

Ohio $  36,839,621 

Pennsylvania 22,726,031 

New  Jersey   ^  15,965,418 


Illinois    

New  York 

Indiana    

Iowa    

West  Virginia   . 

Missouri    

California   

All  other  states, 


14,791,938 
9,489,002 
7,090,630 
6,743,615 
6,284,527 
5,431,569 
3,599,375 

34,158,506 


Percentage. 
22.58 
13.93 

9.79 

9.07 

5.82 

4.35 

4.13 

3.85 

3.33 

2.21 
20.94 


Total  all  states $163,120,232 


360  BUILDING    STONES   AND    CLAYS 

REFERENCES 

Baker,  I.  O.  A  Treatise  on  Masonry  Construction ;  John  Wiley 
and  Sons,  New  York,  1913. 

Bleiningers,  A.  V.  The  Effect  of  Heat  Upon  Clays;  T.  A. 
Randall  and  Co.,  Indianapolis,  Ind.,  1911. 

Hodson,  F.  T.  The  20th.  Century  Bricklayer's  and  Mason's 
Assistant;  F.  J.  Drake  and  Co.,  Chicago,  1905. 

Howe,  M.  A.  Masonry ;  John  Wiley  and  Sons,  New  York, 
1915. 

Kidder,  F.  E.  Building  Construction  and  Superintendence  ;  Wm. 
T.  Comstock,  New  York,  1906. 

Munby,  A.  E.  The  Chemistry  and  Physics  of  Building  Mate- 
rials;  D.  Van  Nostrand  Co.,  New  York,  1909. 

Ries,  H.  Clay,  Its  Occurrence,  Properties,  and  Uses  ;  John  Wiley 
and  Sons,  New  York,  1906. 

Ries,  H.  The  Clays  of  Florida;  U.  S.  Geol.  Survey  17th.  Ann. 
Kept.,  Pt.  Ill,  p.  871,  1898. 

Ries,  H.  The  Clays  of  the  United  States  East  of  the  Mississippi 
River;  U.  S.  Geol.  Survey,  Professional  Paper  No.  11,  1903. 

Ries,  H.  and  Leighton,  H.  History  of  the  Clay  Working  Indus- 
try of  the  United  States ;  John  Wiley  and  Sons,  New  York, 
1908. 

Rowe,  J.  P.  Some  Economic  Geology  of  Montana ;  Univ.  of 
Montana  Bull.  No.  50,  1908. 

Searle,  A.  B.     Modern  Brick  Making;  London,   1911. 

Veatch,  O.  Kaolins  and  Fire  Clays  of  Central  Georgia:  U.  S. 
Geol.  Survev  Bull.  315.  1907. 


CHAPTER  XI 

PAVING  MATERIALS 
PAVING  BRICK 

History. — Paving  brick  are  reported  to  have  been  in  use  in 
Holland  for  more  than  100  years.  They  appear  to  have  been  in 
use  in  the  northern  part  of  England  for  more  than  half  a  century. 
They  were  first  used  in  the  United  States  in  Charlestown,  West 
Virginia,  in  1870.  In  1873  a  block  on  the  principal  business 
street  of  the  same  city  was  paved  with  brick.  This  pavement  was 
still  in  service  after  a  lapse  of  more  than  30  years.  In  1875  a 
block  of  brick  pavement  was  laid  on  a  leading  street  of  Bloom- 
ington,  Illinois.  The  material  was  an  inferior  building  brick, 
but  it  continued  in  service  for  more  than  20  years. 

Today  brick  is  the  only  paving  material  employed  in  most  of 
the  smaller  cities  of  the  Mississippi  Valley.  It  is  used  extensively 
in  many  of  the  larger  cities  of  the  same  territory.  The  use  of 
brick  in  all  parts  of  the  country  for  residence  streets  and  light 
traffic  business  streets  is  rapidly  increasing.  There  are  in  Amer- 
ica approximately  200  plants  devoted  to  the  manufacture  of  pav- 
ing brick.  The  output  of  an  individual  plant  sometimes  surpasses 
in  a  single  year  100,000,000  bricks. 

Definition. — A  paving  brick  is  simply  a  brick  that  will  resist 
the  crushing  and  abrading  action  of  the  traffic  to  which  it  is 
subjected.  Such  brick  require  a  careful  selection  of  the  clay 
and  a  skillful  manufacture. 

The  Clay. — Three  distinct  classes  of  clays  are  employed  in 
the  manufacture  of  paving  brick:  (1)  Surface  clays.  (2)  Im- 
pure fire  clays.  (3)  Shales.  While  surface  clays  are  extensively 
used  in  the  manufacture  of  building  brick  they  are  ordinarily 
unsuitable  for  making  paving  brick.  It  is  practically  impossible 
to  burn  surface  clays  hard  enough  for  paving  brick  without  their 
losing  their  shape.  Pure  fire  clay  on  account  of  its  infusibility 
is  not  well  adapted  for  making  paving  brick.  Such  brick  are 
expensive  to  burn,  lack  density,  hardness  and  strength.  Impure 
fire  clay  makes  a  fair  quality  of  paving  brick.  The  process  of 
manufacture  is  rather  expensive.  Such  bricks  vary  in  color  from 
cream  to  buff  and  absorb  from  2.5  to  7  per  cent  of  water.  Most 
paving  bricks  are  now  made  from  shale  for  this  material  makes  a 
better  and  cheaper  paving  brick  than  either  surface  or  fire  clay. 

361 


362 


BUILDING    STONES   AND    CLAYS 


Slate  can  not  be  rendered  plastic  by  grinding  and  mixing  with 
water.  Shales  may  frequently  be  distinguished  from  fire  clay  by 
the  conchoidal  fracture  of  the  former  material.  (See  Figs.  281 
and  282.) 

Manufacture. — Soft  homogeneous  clays  are  run  through  roll- 
ers to  crush  the  lumps,  and  from  the  crusher  the  material  goes 
directly  to  the  brick  machine.  It  is  usually  desirable  to  run  the 
material  first  through  a  pug  mill,  where  it  is  mixed  and  worked 


Fig.  281. — Scene  in  a  shale  pit  showing  the  joint  system  and 
fracture  of  the  shale,  also  the  method  of  loading  cars  with  shale. 
By  courtesy  of  the  National  Paving  Brick  Manufacturers  Association. 

with  water  into  a  plastic  mass.  Hard  clays  and  shales  are  often 
reduced  in  a  dry  pan  to  a  fine  powder.  The  dry  pan  consists  of 
two  heavy  rollers  or  wheels  which  run  in  a  revolving  pan  that  has 
a  perforated  bottom.  It  is  necessary  that  the  clay  should  be 
reduced  to  an  impalpable  powder  for  four  reasons:  (1)  The 
product  fuses  at  a  lower  temperature.  (2)  The  production  is 
of  an  even  and  close-grained  texture.  (3)  The  resulting  brick 
are  tougher.  (4)  The  brick  are  more  impervious.  The  pow- 
dered and  screened  clay  is  tempered  with  water  in  the  pug  mill 


P AV ING    MATERIALS 


363 


or  a  wet  pan  which  differs  from  the  dry  pan  in  that  the  bottom 
is  water  tight.  The  wet  pan  is  said  to  give  better  results  than 
the  pug  mill  for  the  material  can  be  retained  in  the  pan  until  it 
is  thoroughly  tempered.  This  process,  however,  requires  a  large 
plant,  much  labor  and  power.  (See  Figs.  283,  284  and  285.) 

Molding. — Most  paving  brick  are  made  of  what  is  known  as 
the  stiff-mud  process.  A  few  yards  still  use  the  old  fashioned 
soft-mud  and  re-pressing  system.  Almost  universally  the  mold- 


Fig.  282. — Car  of  shale,  which  has  been  loaded  with  a  steam  shovel, 
ready  to  be  dumped  into  the  crushing  machine.  Here  the  primary 
crusher  receives  a  whole  car  load  of  shale  at  once.  In  this  crusher 
the  shale  is  broken  into  fragments  not  exceeding  six  inches  in 
diameter.  The  shale  then  passes  to  a  secondary  crusher  in  which  the 
shale  is  further  reduced  to  fragments  not  exceeding  three  inches  in 
diameter.  The  crushed  shale  passes  from  the  secondary  crusher  into 
the  dry  pan.  By  courtesy  of  the  National  Paving  Brick  Manufac- 
turers Association. 


ing  is  done  by  an  auger  machine  which  forces  the  tempered  clay 
or  stiff  mud  through  a  die.  This  gives  a  continuous  bar  of  com- 
pressed clay  which  passes  under  an  automatic  machine  that  cuts 
the  bar  into  brick  of  uniform  size.  (See  Fig.  286.) 

Re-pressing. — After  leaving  the  molding  machine  stiff-mud 


364 


BUILDING    STONES   AND    CLAYS 


brick  are  usually  re-pressed.  Re-pressed  brick  are  more  sym- 
metrical in  form  and  therefore  make  a  smoother  pavement.  It  is 
not  certain  that  the  breaking  of  the  bond  of  clay  in  the  process 
of  re-pressing  does  not  diminish  the  strength  and  decrease  the 
durability  of  the  brick.  (See  Fig.  287.) 

Drying. — The  molded  or  re-pressed  brick  are  placed  on  cars 
or  trucks  and  conveyed  to  the  drying  house.  Here  they  should  be 
thoroughly  dried  for  drying  facilitates  the  burning  process.  (See 
Figs.  288  and  289.) 


Fig.  283. — Looking  into  a  primary  crusher.  By  courtesy  of  the 
National  Paving  Brick  Manufacturers  Association. 

Burning. — Paving-  brick  are  usually  burned  in  down-draft 
brick  ovens  with  fire  pockets  or  furnaces  built  in  their  outer  walls. 
The  bottoms  of  the  kilns  are  perforated  that  the  expelled  gases 
may  pass  through  the  flues  which  are  beneath  the  floors  and  which 
lead  to  the  chimney.  The  fire  passes  up  through  the  furnaces  into 
the  kilns  and  then  down  through  the  brick  to  be  burned  to  the 
flues,  and  from  thence  to  the  chimney.  The  initial  fire  is  low  that 
the  water  may  be  expelled  without  cracking  the  brick.  Even 
thoroughly  dried  brick  contain  from  20  to  30  per  cent  of  water. 


P AV ING   MATERIALS 


365 


After  the  water  smoking  has  ceased  the  fires  are  gradually 
increased  until  the  temperature  through  the  kiln  is  sufficient  to 
vitrify  the  brick.  Most  shales  vitrify  at  from  900  to  1,000  de- 
grees C.  while  some  impure  clays  require  a  temperature  of  1,300 
degrees  C.  for  vitrification.  The  time  required  to  raise  the 
temperature  of  the  entire  kiln  to  the  point  of  vitrifying  varies 
from  7  to  10  days.  (See  Figs.  290,  291,  292  and  293.) 

Size. — The  size  of  paving  brick  is  usually  2"x4"x8".    Paving 


Fig  284. — Crushed  shale  passing  on  a  belt  conveyor  from  the 
secondary  crusher  to  the  dry  pan.  By  courtesy  of  the  National 
Paving  Brick  Manufacturers  Association. 


blocks  are  usually  3"x4"x9".  Unfortunately  there  is  a  consider- 
able variation  in  size  in  different  parts  of  the  country.  (See 
Fig.  294.) 

Form.-^The  usual  form  of  brick  is  with  flat  sides  and  square 
corners.  Three  variations,  however,  are  in  somewhat  common 
use  (1)  Rounded  corners  to  prevent  slipping.  (2)  Grooves  on 
the  sides  and  ends  to  increase  the  holding  power  of  the  material 
used  to  fill  the  joints  between  the  brick.  (3)  Raised  letters  or 


366 


BUILDING    STONES   AND    CLAYS 


buttons  on  the  sides  to  hold  the  bricks  apart  and  to  facilitate  the 
introduction  of  the  joint  filler.  (See  Figs.  295,  296,  297,  and 
298.) 

Figures  295,  296  and  297  show  different  forms  of  the  grooves 
employed  to  facilitate  the  introduction  of  the  joint  filler  and  to 
increase  its  holding  power.  The  first  two  are  objectionable  for 
the  brick  spalls  off  from  the  edge  down  to  the  groove,  especially 
when  the  joints  are  filled  with  sand.  Fig.  296  is  better  than  295 
for  the  vertical  grooves  facilitate  the  introduction  of  the  joint 
filler.  It  would  be  better  to  have  the  vertical  grooves  extend  clear 


Fig.  235. — Feeding  a  dry  pan.  By  courtesy  of  the  National  Paving 
Brick  Manufacturers  Association. 

across  the  face  of  the  brick.  Fig.  297  is  a  little  less  objectionable 
than  any  of  the  others.  Fig.  298  represents  either  295  or  296 
cut  in  two  pieces  and  the  two  halves  placed  side  by  side. 

The  name  of  the  manufacturer  often  appears  in  sunken  letters 
on  the  sides  of  the  brick  for  two  reasons:  (1)  The  purpose  of 
advertising.  (2)  To  increase  the  holding  power  of  the  material 
used  to  fill  the  joints.  The  grooves  and  the  sunken  letters  are  all 
added  in  the  process  of  re-pressing. 

Requisites.1—  (1)  Paving  brick  should  be  reasonably  perfect 


P AV ING    MATERIALS  36? 

in  shape.  (2)  They  should  be  free  from  any  marked  warping  or 
distortion.  (3)  They  should  be  uniform  in  size  so  as  to  fit  closely 
together  and  make  a  smooth  pavement.  (4)  They  should  be 
hard  so  as  to  resist  the  crushing  action  of  the  wheels  of  vehicles. 
(5)  They  should  be  tough  so  as  to  resist  the  abrading  action  of 
traffic.  (6)  They  should  be  homogeneous  in  texture.  (7)  They 
should  be  free  from  laminations  or  seams.  (8)  They  should  be 
of  the  same  grade.  The  last  three  requisites  are  necessary  that 
the  brick  may  wear  uniformly. 


Fig.  286. — A  cutting  table  cutting  the  stream  which  flows  from  the 
compressing  machine  into  rectangular  pieces  the  size  of  brick.  By 
courtesy  of  the  National  Paving  Brick  Manufacturers  Association. 

Testing. — The  testing  of  brick  by  well  established  methods 
is  necessary  for  two  reasons :  (1)  To  determine  whether  the  brick 
are  suitable  for  paving  purposes.  (2)  To  enable  comparisons  to 
be  made  between  different  classes  of  brick. 

Specific  Gravity. — The  density  of  paving  brick  depends  largely 
upon  the  character  of  the  original  clay  employed  and  the  kind  of 
fuel  used  in  the  burning  of  the  brick.  The  specific  gravity  may 
be  determined  by  weighing  the  brick  in  air.  Then  saturating  the 


368 


BUILDING    STONES   AND    CLAYS 


brick   with   water   and   weighing   in   air   a   second   time.      Then 
weighing  the  brick  in  water.     The  formula  in  general  use  is : 

Specific  gravity  *     ^m   ' 

Crushing  Strength. — There  are  three  well  known  methods  of 
testing  the  crushing  strength,  employing  respectively  (1)  cubes, 
(2)  half  bricks,  or  (3)  whole  bricks,  in  the  testing  machine. 
Equal  distribution  of  the  pressure  over  the  whole  surface  is 


Fig.  287. — A  series  of  repressing  machines  at  work.  By  courtesy 
of  the  National  Paving  Brick  Manufacturers  Association. 

insured  by  grinding  the  compressed  surface  accurately  to  planes, 
by  the  use  of  a  thin  coat  of  plaster  of  Paris,  or  by  the  insertion 
of  layers  of  blotting  paper,  cardboard,  etc.  The  brick  may  be 
tested  on  end,  edgewise  or  flatwise. 

Tests  on  cubes  show  that  paving  brick  vary  in  their  crushing 
strength  from  10,000  to  20,000  pounds  to  the  square  inch.  The 
load  should  be  applied  uniformly  to  the  flattened  surface  by 
whatsoever  method  this  surface  may  have  been  produced. 

Transverse  Strength. — This  test  is  usually  made  by  placing  the 


P AV ING    MATERIALS 


369 


brick  upon  two  knife-edges  and  applying  a  steady  pressure  on  the 
upper  side  of  the  brick  through  a  third  knife-edge  placed  midway 
between  the  other  two.  The  result,  expressed  in  terms  of  the 
modulus  of  rupture,  is  computed  by  the  following  formula:: 


R  represents  the  modulus   of   rupture  in  pounds  per  square 
inch,    W  the   breaking  load  in   pounds,   /  the   distance  between 


Fig.  288. — Cars  of  brick  at  the  discharged  end  of  the  dry  pan.     By 
courtesy   of   the    National    Paving    Brick    Manufacturers    Association. 

supports  in  inches,  b  the  breadth  of  the  brick  in  inches,  and  d 
the  depth  of  the  brick  in  inches.  The  modulus  of  rupture  usually 
varies  from  2,000  to  3,000  pounds. 

Absorption. — The  absorptive  power  of  a  brick  is  regarded  as  a 
measure  of  the  porosity  of  the  brick,  or  the  degree  of  vitrification. 
When  the  tests  are  conducted  according  to  the  directions  given 
in  the  Report  of  Paving  Brick  Commission  of  National  Brick 
Manufacturers  Association,  pp.  62-63,  (T.  A.  Randall  &  Co.,  In- 
dianapolis, Ind.),  shale  paving  brick  usually  show  less  than  2  per 
24 


370 


BUILDING    STONES   AND    CLAYS 


cent  of  absorption  with  some  of  the  best  brick  ranging  from  0.75 
to  1.50  per  cent.  Tests  showing  less  than  0.5  per  cent  of  absorp- 
tion indicates  an  over-burned  and  brittle  brick.  Good  paving 
brick  made  of  impure  fire  clay  rarely  absorb  less  than  2.5  per 
cent  of  moisture,  and  often  over  5  per  cent. 

Impact  and  Abrasion. — This  is  the  most  crucial  test  of  paving 
brick.  It  exceeds  in  importance  all  other  tests  combined.  The 
results  are  jointly  dependent  upon  four  factors:  (1)  The  tough- 


Fig.  289. — Setting  the  brick  in  the  kiln  after  they  have  dried.  By 
courtesy  of  the  National  Paving  Brick  Manufacturers  Association. 

ness  of  the  brick.  (2)  Its  ability  to  resist  shock.  (3)  Its  hard- 
ness. (4)  Its  power  to  resist  abrasion. 

The  test  is  made  by  rolling  or  tumbling  the  brick,  with  or 
without  fragments  of  iron,  in  a  foundry  rattler  or  cast  iron 
barrel.  There  are  many  modification  of  the  process. 

Merits  of  Brick  Pavements. — Paving  bricks  have  many  at- 
tractive features:  (1)  They  may  be  purchased  in  small  units  of 
practically  uniform  size.  (2)  They  may  be  secured  in  large  or 
small  quantities.  (3)  They  may  be  laid  rapidly  without  expert 
labor.  (4)  When  pipe  lines  are  injured,  demanding  a  disturbance 


PAVING    MATERIALS 


371 


of  the  pavement,  ordinary  tools  and  intelligence  can  restore  the 
original  surface.  (5)  Brick  pavements  give  a  good  foot  hold  for 
horses.  (6)  They  do  not  wear  slippery.  (7)  They  are  adapted 
to  all  grades.  (8)  They  offer  no  tractive  resistance  when  the 
joints  are  filled  with  Portland  cement.  (9)  They  are  not  noisy 
when  properly  laid.  (10)  They  yield  but  little  mud  or  dust. 
(11)  They  are  easily  cleaned.  (12)  They  are  only  slightly 
absorbent  when  the  joints  are  filled  with  sand,  and  non-absorbent 


Fig.  290. — A  scene  showing  how  a  section  of  the  continuous  kiln 
is  being  emptied  of  brick  ready  for  market.  By  courtesy  of  the 
National  Paving  Brick  Manufacturers  Association. 

when  filled  with  tar  or  cement.  (13)  They  are  pleasing  in 
appearance.  (14)  They  are  very  durable  when  the  joints  are 
filled  with  Portland  cement.  (15)  They  are  easily  repaired.  (See 
Fig.  299.) 

Recently  the  monolithic  style  of  construction  has  been  intro- 
duced for  brick  pavements.  Here  the  sand  cushion  has  been 
entirely  eliminated  and  the  bricks  are  laid  on  the  concrete  founda- 
tion before  the  concrete  is  fully  hardened. 

Price  of  Brick  for  Pavements. — The  price  of  paving  brick 


372 


BUILDING    STONES   AND    CLAYS 


be  3 


OCQ 


a  O 
^  o 
O 


3 


PAVING    MATERIALS 


373 


varies  largely  with  the  locality.  The  freight  rate  is  an  important 
factor  in  determining  cost.  The  price  per  thousand  at  the  kiln 
is  usually  between  $8.00  and  $10.00. 

STONE  PAVEMENT 

History. — Hornblendic  rocks  were  used  in  paving  the  streets 
of  Rome  prior  to  the  advent  of  the  Christian  Era.  The  roads  of 
the  Romans  were  constructed  in  fairly  straight  lines,  with  but 
little  regard  to  topography  or  natural  obstacles.  The  roads  were 


Fig.  292. — A  modern  rectangular  kiln.  By  courtesy  of  the  National 
Paving  Brick  Manufacturers  Association. 

costly  in  construction  but  permanent.  The  earliest  dressed  stone 
pavement  in  the  United  States  was  laid  on  Broadway,  New  York 
City,  1849.  The  material  used  was  rectangular  granite  blocks. 

Size  of  blocks. — Many  of  the  blocks  of  stone  now  used  for 
paving  purposes  are  from  8  to  10  inches  in  length,  7  to  8  inches 
in  width  and  from  3  to  4  inches  in  thickness.  Some  of  the 
blocks  of  granite  which  are  too  small  for  monumental  and  con- 
structional stone  are  now  manufactured  into  paving  stone.  This 
material  was  formerly  a  waste  product  at  the  quarry  but  it  now 
becomes  an  important  by-product. 

Granite.  —  Granite    is   more    largely    employed   for   paving 


374 


BUILDING    STONES   AND    CLAYS 


blocks  than  any  other  variety  of  stone.  Granites  are  generally 
regarded  as  the  hardest  and  most  durable  of  stone  paving  blocks. 
There  are  a  few  notable  exceptions.  A  granite  abnormally  high  in 


1 


Fig.  293. — Removing  the  finished  brick  from  a  round  down  draft 
kiln.  By  courtesy  of  the  National  Paving  Brick  Manufacturers 
Association. 

its  quartz  content  is  too  brittle  for  paving  purposes.  A  granite 
containing  too  much  of  the  feldspars  is  easily  decomposed.  A 
granite  exceedingly  rich  in  its  mica  content  is  too  easily  split  for 
use  in  paving  blocks.  This  condition  holds  especially  true  of 


P AV ING   MATERIALS 


375 


granite  gneiss.  Gneisses  that  result  from  the  metamorphism  of 
ieldspathic  sediments  are  too  much  stratified  for  paving  blocks. 
When  quartz  fails,  and  the  ferromagnesian  mineral  is  hornblende, 
the  resulting  syenite  makes  one  of  the  best  of  stone  paving  mate- 
rials. As  a  rule  the  richer  in  hornblende  the  syenite  is  the  better 
the  paving  stone  will  be. 

The  granitic  rocks  of  the  Appalachian  belt,  together  with  those 


Fig.  294. — Manufactured  brick  coming  out  of  the  kiln  on  a  gravity 
carrier.  An  inspector  is  standing  next  to  the  door  rejecting  the  brick 
not  going  into  the  class  of  those  being  loaded  into  the  car  for  ship- 
ment. By  courtesy  of  the  National  Paving  Brick  Manufacturers 
Association. 

of  California,  South  Dakota  and  Wisconsin,  are  largely  used  in 
the  manufacture  of  paving  blocks. 

Trap. — These  dark  colored,  hard,  compact  and  tough  igneous 
rocks  are  not  easily  broken  into  standard  sizes  for  paving  blocks, 
because  they  lack  the  characteristic  rift  and  grain  of  the  granites. 
They  are  resistant  and  durable  but  expensive  to  work.  For  these 
reasons  they  are  not  widely  used  for  paving  blocks.  They  are 
abundant  along  the  Connecticut  River  in  New  England  and  the 


376 


BUILDING    STONES   AND    CLAYS 


Hudson  River  in  New  York.     They  are  extensive  in  New  Jersey, 
in  California  and  in  Oregon. 

Sandstone. — Sandstones  are  much  used  for  paving  purposes 
because  (1)  They  are  easily  worked.  (2)  They  are  sufficiently 
"abundant.  (3)  They  are  widely  distributed.  (4)  They  are 


"^ —        '      i — 

Fig.  295. — Grooved  paving  block.     Drawing  by  L.   W.   Kesler 


Fig.    296. — Grooved   paving   block.     Drawing  by   L.   W.    Kesler. 

resistant  to  abrasion.     (5)  They  do  not  wear  slippery  like  many 
granites. 

The  Potsdam  sandstone  of  New  York,  which  consists  of  quartz 
grains  bound  together  with  a  cement  of  silica,  has  been  extensively 
used  for  paving  purposes.  The  same  holds  true,  especially  in 


PAVING    MATERIALS 


377 


many  cities  bordering  the  Great  Lakes,  for  the  Medina  sandstone 
of  New  York.  The  quartz  grains  of  this  sandstone  are  cemented 
together  with  the  oxide  of  iron  and  a  little  calcium  carbonate. 
The  stone  is  durable.  The  sandstones  of  Boulder  county,  Colo- 


Fig.  297. — Grooved  paving  block.     Drawing  by    L.   W.    Kesler. 


Fig.  298. — A  grooved  paving  block  cut  in  two  pieces  and  the  two 
halves  placed  side  by  side.     Drawing  by  C.  H.   Richardson. 

rado,  are  hard  and  tough.  They  wear  well  in  a  pavement. 
Although  in  time  they  wear  to  a  smooth  surface  they  do  not 
become  slippery.  The  Kettle  River  sandstone  which  is  fine 
grained  and  quarried  extensively  at  Sandstone,  Minnesota,  wears 


378 


BUILDING    STONES   AND    CLAYS 


flat  and  is  largely  used  for  paving  purposes  in  Minnesota  and 
Wisconsin.  The  Sioux  Falls  quartzite  of  Sioux  Falls,  South 
Dakota,  consists  almost  wholly  of  silica.  There  is  just  enough 


Fig.   299. — Section  of  a  brick  pavement  with  brick  foundation.     By 
courtesy  of  I.  O.  Baker. 


Fig.    300. — Section  of   stone-block  pavement.     By  courtesy  of   I.   O. 
Baker. 

of  the  oxide  of  iron  present  to  impart  a  reddish  color  to  the 
stone.  It  is  one  of  the  most  resistant  to  abrasion  of  all  paving 
stone,  yet  it  wears  smooth  with  a  somewhat  glassy  surface. 


PAVING    MATERIALS 


379 


Limestone. — Some  varieties  of  limestone  are  fairly  dense  and 
strong.  Such  varieties  are  often  used  for  paving  purposes.  They 
wear  unevenly.  They  are  easily  broken  by  heavy  traffic  and 
split  by  frost.  Limestones  are  widely  distributed  and  usually 
they  are  easily  worked  into  paving  blocks.  (See  Fig.  300.) 

ROAD  BUILDING  ROCKS 

Requisites. — (1)  A  suitable  road  stone  should  be  soft  enough 
to  grind  to  dust  slowly  under  the  traffic  to  which  it  is  subjected. 
(2)  The  dust  should  have  a  high  cementing  power.  (3)  The 


Fig.  301. — Limestone  quarry,  Prospect,  Oneida  County,  New  York. 
Photo,  by  M.  C.  Collister. 

separate  fragments  of  the  stone  should  have  sufficient  strength 
to  resist  the  crushing  action  of  the  wheels.  Where  the  traffic  is 
light  a  hard  stone  may  not  furnish  enough  dust  to  replace  that 
blown  away  by  the  wind,  washed  away  by  the  water,  and  to  bind 
the  surface.  In  such  a  case  a  softer  stone,  or  one  with  a  higher 
cementing  power  is  preferable. 

Trap. — This  is  a  popular  term  applied  to  any  dark  colored, 
massive,  igneous  rock.  Trap  is  a  very  compact  and  elastic  rock. 
It  has  a  high  resistance  to  crushing  without  being  too  brittle.  Its 


380  BUILDING    STONES   AND    CLAYS 

dust  has  the  cementing  power  in  a  high  degree.  The  different 
traps  are  not  uniformly  desirable  for  purposes  of  road  construc- 
tion but  nearly  all  of  them  are  better  than  the  best  of  other  rocks. 
The  basic,  igneous  rocks,  called  traps,  should  be  placed  first  in 
the  order  of  utility  amongst  all  road  building  stone. 

Granite. — Next  in  value  to  the  trappean  rocks  as  road  metal 
are  those  commonly  called  granites.  An  essential  feature  of 
granite  is  an  evenly  granular  structure  coarse  enough  to  be  dis- 
tinctly visible  to  the  naked  eye.  They  vary  somewhat  in  value, 
but  as  a  rule  they  are  considered  inferior  road  metal  for  three 
reasons.  (1)  Their  coarsely  granular  texture.  (2)  The  brittle- 
ness  of  both  the  requisite  quartz  and  feldspars.  The  low  cement- 
ing power  of  its  dust.  If  the  quartz  fails  so  that  the  rock  may 
be  technically  called  a  syenite  it  is  the  best  for  road  metal 
amongst  the  various  types  of  holocrystalline  rocks.  The  gneis- 
soid  granites  make  a  very  inferior  road  material. 

Felsite. — This  hard  flinty  rock  has  about  the  same  composi- 
tion as  a  granite.  To  the  unaided  eye  it  appears  homogeneous.  It 
is  sometimes  classified  amongst  road  metals  as  a  granite.  It  is 
particularly  high  in  its  cementing  power. 

Limestone. — Limestones  are  usually  deficient  in  hardness 
and  toughness  for  road  metal.  They  possess  cementing  power  in  a 
fair  degree.  The  best  limestones  for  road  metal  require  three 
factors  :  ( 1 )  The  layers  of  the  limestone  should  be  comparatively 
thin.  (2)  There  should  be  little  sign  of  crystallization.  (3) 
They  should  contain  less  than  25  per  cent  of  clayey  matter.  (See 
Figs.  301  and  302.) 

In  proportion  as  limestone  assumes  the  crystalline  character  of 
marble  its  value  as  a  road  metal  diminishes,  for  its  crystalline 
structure  in  most  cases  so  far  weakens  the  mass  that  it  is  apt 
readily  to  pass  into  the  state  of  powder.  Marbles  have  a  high  per 
cent  of  \vear  and  a  low  cementing  power  according  to  the  reports 
compiled  by  the  Massachusetts  Highway  Commission  1896-1901. 

Sandstone. — Sandstones  are  deficient  as  road  metal  for  two 
reasons:  (1)  They  are  easily  reduced  to  sand.  (2)  They  are 
deficient  in  binding  power.  They  are,  however,  highly  resistant 
to  abrasion  and  impact.  In  some  instances  sandstones  have 
sufficient  binding  material  between  the  individual  grains  to  hold 
the  mass  firmly  together  in  such  a  manner  as  to  render  them  fair 
road  building  materials. 

Chert,  which  is  the  variety  of  quartz  that  breaks  with  a 
splintery  fracture  rather  than  conchoidal,  will  usually  give  fairly 
good  results  as  a  road  metal.  It  is  of  great  value  when  it  occurs 


P AV ING   MATERIALS 


381 


in  those  portions  of  the  country  where  good  road  building  mate- 
rials are  scarce  or  entirely  wanting. 

Shale. — For  engineering  purposes  when  the  indurated  clay  is 
nearly  pure  it  is  termed  an  argillaceous  or  clay  shale.  When  it 
contains  a  considerable  amount  of  sand  it  is  termed  an  arenaceous 


Fig.  302. — Stone  crushing  plant,  Prospect,  Oneida  County,  New 
York.  Photo,  by  M.  C.  Collister. 

or  sandy  shale.  For  road  building  the  argillaceous  shales  are 
worthless  and  the  arenaceous  shales  are  useful  only  for  a  top 
dressing.  They  are  not  satisfactory  even  for  that  purpose. 

Slate. — As  a  road  metal  the  fragments  of  slate  quickly  grind 
to  a  dust  which  has  but  little  binding  power.  Slate  makes  a 
smooth  road,  but  one  that  wears  away  rapidly  when  wet.  It  is 
sometimes  used  as  a  surfacing  or  binding  material,  but  it  is  much 
inferior  to  clean  sand  or  good  stone  dust. 


382 


BUILDING    STONES   AND    CLAYS 


Field  Stones. — In  many  glaciated  districts  an  excellent  road 
material  may  be  obtained  by  crushing  the  various  boulders  and 
pebbles  that  are  too  coarse  for  use  in  gravel  roads.  In  northern 
New  England  the  complex  mixture  of  the  basic  and  acidic  intrus- 
ives  with  the  metamorphosed  sedimentaries  has  produced  a  very 
satisfactory  permanent  road.  Whenever  glacial  boulders  are 
badly  decomposed  they  are  essentially  unfit  for  road  building. 
(See  Fig.  303.) 


Fig.  303. — Sand  and  gravel  deposit  in  Northern  Vermont,  used  in 
making  permanent  roads.  Photo,  by  C.  H.  Richardson. 

For  further  information  concerning  the  road  building  rocks  of 
the  United  States  the  student  is  referred  to  the  Preliminary 
Report  on  the  Geology  of  the  Common  Roads  of  the  United 
States,  by  N.  S.  Shaler,  U.  S.  Geological  Survey,  Fifteenth 
Annual  Report,  1893-189-1,  pp.  255-206. 

For  references  to  standard  works  bearing  in  part  on  paving 
brick  see  list  of  references  at  the  close  of  chapter  X. 


CHAPTER  XII 

CEMENT  AND  CONCRETE 
CEMENT 

History. — The  extensive  use  of  concrete  in  recent  years  has 
led  many  to  speak  of  the  cement  industry  as  a  new  industry,  and 
the  present  as  the  Age  of  Concrete.  Hydraulic  cement  has 
been  used  in  some  form  since  the  dawn  of  civilization.  The 
Egyptians  more  than  4,000  years  ago  manufactured  natural 
cement.  500  years  before  the  beginning  of  the  Christian  Era  an 
aqueduct  some  70  miles  in  length  was  constructed  of  natural 
cement  to  supply  the  city  of  Carthage  with  water.  The  ancient 
Greeks  and  Romans  used  hydraulic  cement  in  the  foundations  of 
many  buildings,  in  superstructures,  water  mains,  sewers  and 
roads.  The  dome  of  the  Parthenon,  erected  at  the  beginning  of 
the  Christian  Era,  is  an  example  of  the  use  of  concrete  construc- 
tion by  the  ancients. 

The  art  of  manufacturing  hydraulic  cement  appears  to  have 
been  lost  during  the  Middle  Ages.  In  1756  it  was  rediscovered 
by  John  Smeaton,  who  burned  argillaceous  limestones  to  manu- 
facture a  lime  that  would  set  under  water.  This  material  was 
used  in  the  construction  of  the  Eddystone  lighthouse. 

In  1796  Joseph  Parker  manufactured  natural  cement,  which 
he  styled  Roman  cement,  by  crushing  and  burning  septaria 
nodules  from  the  Isle  of  Sheppey,  off  the  coast  of  England.  In 
1802  at  Boulogne,  France,  natural  cement  was  manufactured 
from  septaria  pebbles  which  were  called  Boulogne  pebbles.  In 
the  interim  from  1813  to  1818,  M.  Vicat  manufactured  hydraulic 
cement  by  mixing  chalks  and  clays.  In  1818  Canvass  White  pro- 
duced natural  cement  from  the  hydraulic  limestone  deposits  near 
Fayetteville,  N.  Y.  Since  that  date  hydraulic  cement  has  been 
extensively  manufactured  in  the  United  States. 

In  1824  Joseph  Aspdin  manufactured  Portland  cement  by  cal- 
cining lime  and  clay.  He  styled  the  product  Portland  cement 
because  the  finished  product  closely  resembled  the  famous  oolitic 
limestone  from  the  Island  of  Portland,  Derbyshire,  England. 
The  limestone,  like  the  oolitic  limestone  of  Bedford,  Indiana,  has 
been  used  extensively  for  constructional  purposes.  In  1825 
Aspdin  established  a  plant  at  Wakefield,  England,  for  the  manu- 
facture of  Portland  cement.  In  1875  the  first  American  Portland 

383 


384 


BUILDING    STONES   AND    CLAYS 


cement  was  manufactured  by  David  O.  Savior,  Coplay,  Pa.  For 
the  next  15  years  the  development  of  the  industry  in  the  United 
States  was  very  slow  but  since  the  year  1890  the  output  has 
assumed  large  proportions.  In  1915  the  output  for  the  United 
States  was  85,732,000  barrels. 

Quick  Lime. — Quick  lime,  or  common  lime,  is  manufactured 
by  burning  pure,  or  somewhat  impure  limestone,  in  kilns  and 
sometimes  grinding  the  burned  product  to  an  impalpable  powder. 
In  the  process  of  burning  the  limestone  the  carbon  dioxide  is 
driven  off  and  lime,  CaO,  remains  in  the  kiln.  If  the  limestone 


Fig.  304. — Niagara  limestone,  Lauer  and  May  limekiln  quarry,  east 
of  Brighton,  New  York,  looking  north  15°  east.  Near  top  of  Lock- 
port.  Photo,  by  H.  L.  Fairchild. 

contains  more  than  12  per  cent  of  impurities  it  possesses  the 
property  of  absorbing  water  with  great  avidity.  This  absorption 
is  accompanied  by  heat  and  the  evolution  of  caustic  vapors,  and 
finally  the  resulting  product  is  a  powder.  The  product  is  slaked 
lime  and  the  process  is  known  as  slaking.  (See  Fig.  30-1.) 

Good  lime  hardens  in  the  air.  It  comes  in  hard  lumps.  In 
the  process  of  slaking  it  increases  in  bulk  from  2l/2  to  3^  times. 
It  will  also  absorb  l/4  its  own  weight  of  water.  When  too  much 
water  is  added  in  the  process  of  slaking  the  lime,  it  forms  a  sort 
of  paste.  Lime  mortar  is  made  by  mixing  slaked  lime  with 


CEMENT   AND    CONCRETE  385 

sand.  This  product  is  used  extensively  for  building  purposes, 
if  not  enough  water  is  added  in  the  slaking  of  the  lime,  and 
more  water  is  then  added,  it  renders  the  lime  granular  and 
lumpy. 

Lime  Mortar. — Lime  mortar  is  manufactured  by  mixing  a 
paste  of  slaked  lime  with  2y2  to  3  volumes  of  clean  sand.  The 
sand  reduces  the  cost  of  construction  and  prevents  the  mortar 
from  cracking.  If  too  much  sand  is  used  the  mortar  will  be 
porous.  Two  processes  are  involved  in  the  hardening  of  the 
mortar.  (1)  The  formation  of  crystals  as  the  lime  gradually 
dries  out.  (2)  The  formation  of  calcium  carbonate  or  limestone 
through  the  absorption  of  carbonic  acid  from  the  atmosphere. 
It  is  obvious  that  lime  mortar  cannot  harden  under  water  or  in 
the  soil  for  crystallization  can  occur  only  on  the  drying  out  of 
the  lime.  The  length  of  time  required  for  lime  mortar  in  a 
thick  wall  to  crystallize  is  well  illustrated  by  the  Scotch  proverb, 
"When  a  hundred  years  are  past  and  gane,  then  gude  mortar 
turns  into  stane." 

Hydraulic  Lime. — Hydraulic  lime  is  manufactured  by  burn- 
ing a  limestone  which  contains  10  per  cent  or  more  of  silica  and  a 
sufficient  amount  of  alumina  to  enable  the  burned  product  to  set 
under  water.  There  is  usually  from  15  to  25  per  cent  of  the 
silica  and  alumina  combined.  The  burned  product  consists  of 
free  slaked  lime  together  with  the  silicates  and  aluminates  of 
calcium. 

The  free  lime  slakes  readily  in  water  but  the  process  is 
retarded  by  the  presence  of  the  silicates  and  aluminates.  If 
hydraulic  lime  is  mixed  with  water  to  form  a  paste  it  can  be  used 
in  the  same  manner  as  quick  lime.  The  material  dries,  hardens 
and  slowly  absorbs  carbon  dioxide  from  the  atmosphere.  If  used 
without  sand  it  swells  and  cracks.  When  used  under  water 
hydraulic  lime  sets  with  more  or  less  rapidity.  The  larger  the 
percentage  of  common  lime  present  the  slower  will  be  the  setting, 
tor  quick  lime  is  inert  under  water  and  in  damp  soil.  The 
setting  is  due  to  the  presence  of  the  combined  lime  which  suffers 
crystallization  in  the  same  manner  as  in  hydraulic  cement. 

Natural  Cement. — American  natural  cement  was  first  called 
Rosendale  cement  because  it  was  first  manufactured  at  Rosen- 
dale,  N.  Y.  Its  manufacture  consists  of  burning  hydraulic  lime- 
stone in  plain  upright  kilns  with  heat  insufficient  to  cause  vitrifica- 
tion, and  subsequently  grinding  the  product  to  a  fine  powder. 
The  unground  product  will  not  slake  with  water.  When  the  fine 
powder  is  mixed  with  water  it  hardens  or  sets  rapidly  both  in 
air  and  in  water.  During  the  process  of  burning  the  carbon 

25 


386  BUILDING   STONES   AND    CLAYS 

dioxide  of  the  limestone  is  driven  off  and  the  lime  combines  with 
the  silicates,  aluminates  and  ferrites  of  calcium.  If  the  limestone 
the  silcates,  aluminates  and  ferrites  of  calcium.  If  the  limestone 
is  dolomitic,  magnesium  compounds  will  result.  According  to 
Prof.  Robert  Fletcher,  Director  of  the  Thayer  School  of  Civil 
Engineering  at  Dartmouth  College,  Hanover,  N.  H.,  the  presence 
of  magnesium  carbonate  up  to  3.5  per  cent  is  not  injurious  to  the 
cement.  Some  good  cements  have  been  manufactured  from 
limestone  containing  between  3.5  and  5  per  cent  of  magnesium 
but  above  that  upper  limit  all  limestones  should  be  rejected  for 
cement  purposes. 

Hydraulic  limestone  is  usually  stratified  and  the  different  layers 
vary  somewhat  in  their  chemical  composition.  Unless  chemical 
analyses  prove  the  stone  from  a  given  quarry  to  be  fairly  con- 
stant in  composition  the  quarried  blocks  are  mixed  so  that  any 
error  from  too  much  silica,  alumina  or  magnesia  in  any  given 
layer  may  be  corrected  in  the  finished  product. 

The  rock  is  generally  quarried  by  the  open  cut  method  where 
the  stripping  is  light.  It  is  sometimes  mined,  rather  than 
quarried,  by  tunnels  and  chambers.  The  quarried  limestone  is 
broken  into  fragments  convenient  for  feeding  into  an  ordinary 
lock  crusher,  which  breaks  it  into  fragments  that  vary  in  size  up 
to  6  inches,  and  then  conveyed  by  an  ordinary  tramway  to  the 
loading  platform  at  the  top  of  the  kiln. 

In  the  process  of  burning  there  is  an  average  loss  of  about  25 
per  cent  of  the  material  from  the  burnt  and  over  burnt  product. 
The  sorted  calcined  rock  is  conveyed  to  rotary  crushing  machines 
where  it  is  reduced  to  the  form  of  a  powder,  screened  and  the 
coarser  particles  reground.  The  whole  product  is  conveyed  from 
the  reducing  mills  to  mixers  where  the  entire  product  is  uniformly 
mixed  and  then  conveyed  by  chutes  to  the  bags  and  barrels  in 
which  it  is  packed  for  storage  and  shipment. 
,  Portland  Cement. — The  term  Portland  cement  is  used  to  de- 
signate the  artificial  product  formed  by  burning  a  mixture  of  lime- 
stone and  clay  in  correct  proportions  to  the  point  of  incipient 
fusion.  Portland  cement  differs  from  natural  cement  both  in 
character  of  the  raw  material  used  and  in  the  quantity  of  heat 
required  in  its  manufacture.  (See  Fig.  305.) 

There  are  5  steps  involved  in  the  process  of  manufacturing 
the  cement:  (1)  The  quarrying  of  the  limestone  and  cement 
rock.  (2)  The  grinding  of  the  raw  materials.  (3)  Proportioning 
and  mixing.  (4)  Burning  the  mixture.  (5)  Grinding  of  the 
clinker. 

1.     The  cement  rock  and  limestone  are  quarried  by  the  open 


CEMENT   AND    CONCRETE 


387 


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rt  C 


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6ft 


388  BUILDING    STONES   AND    CLAYS 

cut  method  or  mined  by  means  of  tunnels  and  chambers.  Cement 
lock  and  limestone  are  the  materials  most  commonly  used  in  the 
manufacture  of  Portland  cement.  Other  materials  sometimes 
used  are  limestone  and  clay,  marl  and  clay,  chalk  and  clay.  The 
raw  materials  should  contain  from  21  to  24  per  cent  of  silica; 
6  to  8  per  cent  of  alumina ;  2  to  4  per  cent  of  iron  oxide  ;  60  to  65 
per  cent  of  calcium  carbonate.  The  per  cent  of  magnesia,  sul- 
phuric acid  and  water  should  be  small. 

2.  In  the  grinding  of  the  raw  materials  two  processes  have 
been  extensively  used.     One  is  known  as  the  wet  process  and  the 
ether  as  the  semi-wet  process.     The  former  is  better  for  soft  or 
wet  materials  as  marl  and  clay,  or  chalk  and  clay.     The  materials 
are  mixed  in  a  vat  or  wash  mill  with  a  large  excess  of  water. 
The  lumps  are  reduced  by  agitators  to  a  finely  divided  state  so 
that  the  material  may  be  held  in  suspension  in  the   excess   of 
water.    The  sediment  is  drawn  off  into  settling  tanks  and  molded 
into  bricks  which  are  dried  and  calcined  in  either  stationary  or 
rotary  kilns. 

3.  In  the  semi-wet  process  the  marl  or  chalk  is  disintegrated 
and  run  into  storage  basins.     The  clay  is  dried,  pulverized  and 
mixed  with  the  proper  amount  of  marl  in  pans.     Enough  water  is 
added  to  this  mixture  to  produce  a  thick  creamy  mass.    The  mix- 
ture is  then  ground  and   run   into  tanks   where   it  is  constantly 
stirred  by  means  of  pedals  or  compressed  air.     The  wet  slurry 
is   pumped   into   rotary   kilns   where    it   is   burned   at   high   tem- 
peratures. 

4.  Rotary  kilns  are  used  exclusively  in  the  United  States  at 
the  present  time  in  the  manufacture  of  Portland  cement.     In  the 
kiln  the   material  is  burned  to  a   clinker.     The  clinkers   should 
appear  in  the  form  of  balls  ranging  in  size  from  sand  grains  up 
to  one  inch  in  diameter. 

5.  The  clinker  emerges  from  the  kiln  at  a  temperature  of  red 
heat.      It    is    cooled   by    water.      When    thoroughly    cooled    it    is 
ground  to  a  powder  so  fine  that  90  per  cent  of  the  product  will 
pass  through  a  100  mesh  sieve.     The  product  is  then  seasoned, 
weighed  out  into  bags  and  barrels  for  storage  or  shipment. 

In  the  dry  process  as  used  for  cement  rock  and  limestone  the 
quarried  product  is  crushed,  mixed,  dried,  ground,  calcined  and 
the  clinker  ground  to  a  powder. 

The  Hudson  and  Catskill  plants  use  the  dry  method  entirely. 
Limestone,  clay  and  coal  (fuel)  are  each  ground  separately; 
the  two  former  are  mixed  and  fed  into  the  upper  end  of  a  rotary 
kiln,  while  the  coal  is  blown  in  from  the  lower  end  of  the  kiln. 
The  clinker  secured  by  this  dry  method  ranges  in  size  up  to  that 


CEMENT   AND    CONCRETE  389 

of  a  man's  head.  The  clinker  is  cooled  by  being  carried  back 
and  forth  on  an  endless  steel  conveyor  and  finally  dumped  into 
a  crusher,  from  which  it  goes  to  the  fourth  set  of  grinders. 
Water  is  not  used  at  any  time  in  this  process. 

White  Portland  Cement. — White  cement  is  manufactured 
from  pure  white  sand,  white  quartz,  white  limestone,  or  ground 
marble.  Although  this  white  cement  or  white  artificial  stone  is 
about  4  times  as  expensive  as  ordinary  Portland  cement  it  is  ex- 
tensively used  in  the  United  States. 

Lewis  and  Chandler  in  their  "Popular  Handbook  for  Cement 
and  Concrete  Users"  give  the  following  summary  of  uses  for 
white  cement: 

1.  Building    ornamentation.      For    exteriors,    steps,    railings, 
columns,  doorways,  windows,  casings,  cornices,  panels. 

2.  Stucco. 

3.  Concrete  building  blocks. 

4.  Interior   decoration.      Staircases,    wainscoting,   panels,    re- 
liefs, floors. 

5.  Statuary.     An  improved   substitute   for  plaster  in   repro- 
ducing  statuary   figures   and   groups    for   galleries    of   casts,    or 
exterior  and  interior  decoration. 

6.  Cemetery  work.     For  monuments,  vaults,  columns,  urns, 
etc. 

7.  Parks  and  grounds.     For  fountains,  seats,  railings,  walks, 
bridges,  etc. 

8.  Tile,  mosaics,  etc.     In  the  production  of  white  or  delicate 
tints  and  as  a  cement  in  the  place  of  Keene's  cement. 

9.  Colored  concrete.     Permits  the  use  of  bright  or  delicate 
colors. 

10.  Painting  iron  or  concrete. 

11.  Stainless  mortar.    For  laying  up  Bedford  limestone,  sand- 
stone or  marble. 

12.  Setting  and  pointing  between  blocks   or  slabs  of   white 
marble,  limestone,  or  brick. 

Pozzuolana. — Pozzuolana  is  often  called  slag  cement.  It  is 
sometimes  classified  as  Portland  cement  by  the  manufacturers. 
It.  differs  materially  from  Portland  cement.  It  is  an  excellent 
cement  for  many  purposes  but  it  possesses  qualities  that  make  it 
objectionable  as  a  substitute  for  Portland  cement  in  many  classes 
of  work.  The  cement  will  set  either  under  water  or  in  the 
open  air.  The  product  derived  its  name  from  the  Italian  city 
Pozzuoli  which  is  situated  near  the  foot  of  Mount  Vesuvius 
where  the  properties  of  cement  produced  by  volcanic  action  were 
first  discovered. 


390  BUILDING    STONES    AND    CLAYS 

In  the  manufacture  of  Pozzuolana  blast  furnace  slags  are  used. 
The  slag  as  it  comes  from  the  furnace  is  shorted  by  water  under 
high  pressure.  In  the  rapid  chilling  of  the  slag  about  one-third 
of  its  sulphur  is  liberated,  while  the  slag  undergoes  other  chem- 
ical changes.  The  granulated  slag  is  mixed  with  quick  lime  and 
ground  to  a  powder  sufficiently  fine  for  95  per  cent  of  the  product 
to  pass  through  a  200  mesh  sieve.  The  slag  is  dried  before 
grinding.  The  lime  is  obtained  from  a  very  pure  limestone. 
Caustic  soda  is  added  in  small  quantities  to  the  water  used  in 
slaking  the  lime  to  render  the  cement  quick  setting. 

Properties  of  Cement. — According  to  H.  A.  Reid  the  desir- 
able properities  in  cement  are :  (1 )  That  when  treated  in  the  pro- 
posed manner  it  shall  at  the  end  of  a  definite  period  develop  a 
certain  strength.  (2)  That  it  shall  contain  no  compounds  which 
may  at  any  future  time  cause  it  to  change  its  form  or  volume,  or 
lose  any  of  its  strength.  (3)  That  it  shall  withstand  the  action  of 
any  outside  agency  which  may  tend  to  decrease  its  strength  or 
impair  its  durability. 

Color. — Variations  in  color  indicate  different  types  of  rock 
used  in  the  manufacture  of  the  cement  or  different  temperatures 
during  the  process  of  burning. 

Portland  cement  is  usually  a  dull  gray.  Bluish  gray  indicates 
an  excess  of  lime.  Brown  an  excess  of  clay.  Dark  green  an 
excess  of  iron.  Yellowish  tints  signify  over  burning. 

Natural  cement  ranges  in  color  from  a  light  yellow  through 
dark  gray  to  a  chocolate  brown. 

Slag  cement  ranges  from  bluish  white  to  lilac  in  color.  There 
is  sometimes  in  slag  cement  a  bluish  green  tint  due  to  the  pres- 
ence of  calcium  sulphide.  Good  slag  cements  do  not  stain  blocks 
of  white  marble  or  creamy  white  sandstones  and  therefore  they 
are  often  used  in  architecture. 

Specific  Gravity. — The  specific  gravity  of  good  Portland  cement 
ranges  from  3.10  to  3.25.  Natural  cement  varies  from  2.75  to 
3.05.  Slag  cement  2.6  to  2.9.  A  higher  specific  gravity  than 
those  given  indicates  an  everburning  of  the  material  which  is  a 
source  of  weakness.  A  lower  specific  gravity  may  indicate  an 
under  burning  of  the  product  or  the  presence  of  adulterants. 
Plaster  of  Paris  is  often  used  as  a  legitimate  adulterant.  It  serves 
as  a  retarder  in  the  setting  of  the  cement.  The  materials  of 
lower  specific  gravity  than  Portland  cement  which  are  sometimes 
used  in  its  adulteration  are  natural  cement,  slag  cement,  unburned 
limestone  and  cinders.  The  age  of  the  cement,  the  fineness  to 
which  it  is  ground  and  its  chemical  composition  may  be  respons- 
ible for  a  low  specific  gravity. 


CEMENT   AND    CONCRETE  391 

Acitivity. — This  is  the  time  required  for  a  cement  to  set  or 
harden.  It  may  harden  so  quickly  that  the  material  is  worthless 
for  architectural  purposes.  It  may  set  so  slowly  that  it  retards 
work  and  increases  expense.  The  initial  set  takes  place  when 
the  material  begins  to  harden.  The  hard  set  occurs  when  the 
mass  can  not  be  appreciably  distorted  without  rupture.  The 
best  cements  acquire  their  initial  set  slowly  and  then  harden 
rapidly. 

Soundness. — A  good  cement  will  not  expand,  contract  or  check 
after  the  initial  set  has  begun.  Unsoundness  in  cement  is  often 
due  to  an  excess  of  either  free  or  loosely  combined  lime.  The 
presence  of  the  excess  of  lime  may  be  due  to  any  one  or  more  of 
several  factors.  (1)  To  incorrect  proportioning.  (2)  To  insuf- 
ficient grinding  of  the  raw  materials.  (3)  To  under  burning  the 
products  in  the  kiln.  (4)  To  insufficient  grinding  of  the  calcined 
rock.  (5)  To  lack  of  seasoning  the  finished  product.  Fresh 
cements  made  of  good  material  will  sometimes  test  unsound,  while 
the  unsoundness  will  disappear  in  a  few  weeks  time. 

Expansion  and  disintegration  may  be  caused  by  an  excess  of 
magnesia,  or  by  alkalies,  or  the  presence  of  sulphides.  Contrac- 
tion may  be  caused  by  an  excess  of  clay.  In  slag  cements  the 
unsoundness  is  generally  due  to  the  presence  of  quicklime,  an 
excess  of  magnesia,  or  the  presence  of  sulphides. 

Fineness. — The  finer  a  cement  is  ground  the  better  will  be  its 
quality  and  the  greater  will  be  its  covering  capacity.  For  Port- 
land cement  92  per  cent  of  its  weight  should  pass  through  a 
100  mesh  sieve.  For  natural  cement  90  per  cent.  For  slag 
cement  97  per  cent  of  its  weight  should  pass  through  a  100  mesh 
sieve. 

Tensile  Strength. — The  tensile  strength  of  cement  is  easily 
determined  and  is  generally  considered  a  true  measure  of  the 
compressive,  transverse,  adhesive  and  searing  values. 

H.  A.  Reid  in  his  "Concrete  and  Reinforced  Concrete  Con- 
struction" gives  the  tensile  strength  for  Portland  cement  28  days 
of  age  (1  day  in  moist  air  and  27  days  in  water)  as  600  Ib. 
Natural  cement  of  the  same  age  and  under  the  same  conditions 
as  225  Ib.  Slag  cement  under  the  same  conditions  as  500  Ib. 

Compressive  Strength. — The  Watertown  Arsenal  Report  of 
1902  gives  the  compressive  strength  of  Portland  cement  gauged 
with  25  per  cent  water  at  the  age  of  1  day  in  air  as  430  Ib.  per 
square  inch.  At  28  days  of  age  in  air  as  3,130  Ib.  at  28  days  of 
age,  1  in  air  and  27  in  water  as  7,580  Ib. 

Chemical  Composition. — The  chemical  composition  is  one  of 
the  most  important  guides  to  the  quality  of  the  product.  The 


392  BUILDING    STONES   AND    CLAYS 

chemist  usually  grinds  the  cement  to  a  very  fine  powder  before 
determining  any  constituent  that  may  be  present.  It  is  advised 
by  some  engineers  that  the  true  nature  of  the  cement  is  best  deter- 
mined without  pulverizing  the  material  or  otherwise  changing 
its  physical  characteristics.  In  this  manner  the  free  silica  which 
is  always  inert  is  separated  from  the  mixture  and  determined 
separately.  The  combined  silica  is  an  active  agent  in  the  setting 
of  the  cement. 

The  average  chemical  composition  of  11  well  known  American 
cements  is  given  for  reference. 

Silica,    SiO2    21 .90% 

Alumina,    A12O3 7.89 

Ferric  oxide,  Fe,O3 3.09 

Lime,  CaO   ". 62.04 

Magnesia,   MgO    2.33 


98.74 

The  following  shows  the  average  composition  of  7  high  class 
American  cements  with  the  soluble  silica  separated  in  the  analysis 
from  the  insoluble  silica. 

Silica,   SiO2   (Soluble)    18.45 

Silica,    SiCX    (Insoluble    in    10    per    cent 

HC1)    ..." 4.38 

Alumina  and  iron  oxides,  A12O3 9.46 

Lime,    CaO    61.89 

Magnesia,  MgO 1.78 

Sulphuric  oxide,  SO3 1.87 


97.83 
CONCRETE 

Advantages  of  Concrete. — The  advantage  of  concrete  for  a 
pavement  foundation  are:  (1)  It  gives  a  smooth  uniform  surface 
upon  which  to  lay  the  pavement.  (2)  It  prevents  the  surface 
water  from  percolating  to  the  subgrade.  (3)  By  its  thickness 
and  resistance  to  flexure,  it  distributes  the  concentrated  load 
over  a  considerable  area  of  the  subgrade.  (4)  Concrete  acts  as 
a  bridge  to  support  the  pavement  in  case  of  a  settling  of  the 
subgrade.  (5)  Being  impervious  to  water  and  a  nonconductor 
of  heat,  concrete  protects  water  and  gas  pipes  from  freezing. 

Theory  of  Concrete. — The  proportions  of  the  concrete  should 
be  so  adjusted  that  the  voids  in  the  sand  will  be  filled  with 
cement  paste,  and  the  voids  in  the  gravel  or  broken  stone  will  be 
filled  with  cement  mortar.  The  cement  is  the  most  expensive  con- 


CEMENT   AND    CONCRETE  393 

stituent.  If  more  cement  or  mortar  is  used  than  is  required  to 
fill  all  the  voids,  the  cost  is  needlessly  great.  The  cement  is 
usually  the  weakest  constituent.  If  more  cement  is  used  than  is 
necessary  the  strength  of  the  concrete  is  correspondingly  de- 
creased. In  a  perfect  concrete  every  grain  of  sand  will  be  coated 
with  cement  paste,  and  every  point  of  each  fragment  of  broken 
stone  will  be  covered  with  cement  mortar. 

Gravel  vs.  Broken-Stone  Concrete. — At  the  same  price  per 
unit  of  volume  broken  stone  is  the  better  for  the  following 
reasons:  (1)  The  cement  adheres  more  closely  to  the  rough  sur- 
faces of  the  angular  fragments  of  the  broken  stone  than  to  the 
smooth  surface  of  the  rounded  pebbles.  (2)  The  resistance  of 
concrete  to  crushing  is  due  in  part  to  the  frictional  resistance  of 
one  piece  of  aggregate  to  moving  on  another.  Therefore  broken 
stone  makes  a  stronger  concrete  than  gravel. 

Portland  Cement  vs.  Natural  Cement. — Formerly  natural 
cement  was  a  trifle  the  cheaper  per  unit  of  strength.  With  the 
present  prices  Portland  cement  is  a  little  the  cheaper. 

Wet  vs.  Dry  Concrete. — Dry  mixtures  of  neat  cement,  and 
also  of  cement  and  sand,  are  stronger  than  wet  mixtures,  pro- 
vided the  amount  of  water  is  sufficient  for  the  crystallization  of 
the  cement.  It  is  also  true  that  in  even  a  dry  mortar  or  concrete, 
the  amount  of  water  is  considerably  in  excess  of  that  necessary 
for  the  crystallization  of  the  cement,  and  this  excess  increases 
with  the  amount  of  sand  and  aggregate.  An  excess  of  water  is 
an  element  of  weakness. 


CHAPTER  XIII 

ARTIFICIAL  STONE 

Several  kinds  of  artificial  stone  are  now  in  use  for  architec- 
tural and  artistic  purposes,  and  for  the  pavements  of  cellars,  for 
footpaths,  areas,  and  other  localities  not  subjected  to  the  tread  of 
heavy  animals  and  vehicles.  They  represent  a  combination  of 
hydraulic  cement,  sand,  pebbles,  crushed  stone,  etc.  Some  of 
them  possess  considerable  merit  and  are  of  value  in  localities 
where  durable  and  cheap  building  stone  is  not  supplied  by 
nature. 

The  strength  and  hardness  of  all  varieties  of  artificial  stone 
vary  directly  with  the  ultimate  strength  and  hardness  attainable 
by  the  hydraulic  ingredients  employed.  The  quality  of  such 
stone  as  a  unit  may  be  improved  by  the  employment  of  only  the 
highest  grades  of  cement. 

Beton-Coignet. — This  stone  as  invented  by  Coignet  of  Paris 
consists  of  Portland  cement,  hydraulic  lime  and  clean  sand, 
mixed  together  with  a  little  fresh  water.  The  peculiarities  of 
the  stone  result  from  (1)  The  small  quantities  of  water  used  in 
its  manufacture.  (2)  A  judicious  choice  of  the  qualities  and 
proportions  of  the  ingredients.  (3)  The  thoroughness  with 
which  the  mixing  is  done.  The  stone  is  nothing  more  than 
hydraulic  concrete  from  which  the  coarse  fragments  have  been 
omitted.  It  is  used  in  France  to  a  considerable  extent  in  the  con- 
struction of  the  walls  of  houses  and  in  repairing  masonry. 

The  so  called  Beton-Coignet  stone  of  America  consists  of  a 
mixture  of  either  natural  or  Portland  cement  and  sand  that  has 
been  mixed,  molded  and  compacted  together  for  constructional 
purposes. 

Portland  Stone. — This  stone  is  a  mixture  of  Portland  cement 
and  sand,  or  sand  and  gravel  compacted  into  form  by  tamping. 
Its  strength  and  hardness  is  dependent  upon  the  grade  of  cement 
employed.  One  part  of  dry  cement  is  usually  mixed  with  two 
or  two  and  one-half  parts  of  sand.  To  insure  the  production  of 
a  homogeneous  stone  the  manipulation  must  be  prolonged  and 
thorough.  It  is  used  for  nagging,  for  grindstones  in  England 
and  for  footpaths,  etc. 
the  fact  that  the  oxychloride  of  magnesium  possesses  hydraulic 

Sorel  Stone. — The  composition  of  this  stone  is  based  upon 

394 


ARTIFICIAL    STONE  395 

energy  in  a  marked  degree.  The  stone  is  manufactured  by  adding 
a  solution  of  the  chloride  of  magnesium  of  the  proper  strength 
and  in  the  proper  proportion  to  the  oxide  of  magnesium.  The 
strength  of  this  stone,  as  well  as  its  hardness,  exceeds  that  of  any 
other  artificial  stone  yet  manufactured.  The  stone  can  be  manu- 
factured cheaply  for  foundations  and  plain  massive  walls  by  in- 
corporating in  its  body  large  pebbles  and  cobble  stones. 

McMurtrie  Stone.— This  stone  consists  essentially  of  the 
Portland  stone  in  the  interstices  of  which  are  formed  compounds 
of  alumina  with  the  fatty  acids  by  the  double  decomposition  of 
alum  and  a  potash  soap.  The  advantages  of  the  stone  are:  (1) 
Its  low  power  of  absorption.  (2)  The  new  products  formed  are 
insoluble  in  water.  (3)  They  are  not  affected  by  the.  carbonic  acid 
of  the  atmosphere.  (4)  They  add  considerably  to  the  early 
strength  of  the  stone.  (5)  They  add  also  to  the  ultimate  strength 
of  the  stone. 

The  water-absorbing  capacity  of  this  stone  is  about  twice  that 
of  granite.  Portland  cement  absorbs  from  10  to  20  per  cent 
of  water.  Mortar  absorbs  from  50  to  60  per  cent  of  its  own 
weight  of  moisture.  This  absorbed  moisture  tends  to  dissolve  the 
soluble  salts  of  lime,  magnesia,  soda  and  potash  which  upon  evap- 
oration leave  a  white  efflorescence  on  the  surface. 

This  stone  has  been  used  in  the  fronts  of  stores  and  dwellings 
and  in  the  window  trimmings  of  the  National  Museum. 

Frear  Stone. — This  stone  is  made  of  gxDod  Portland  cementr 
siliceous  sand  and  gum  shellac.  The  inventor  of  the  stone  used 
one  part  of  cement  with  two  and  one-half  parts  of  sand  moistened 
with  an,  alkaline  solution  of  shellac  of  sufficient  strength  to 
furnish  an  ounce  of  the  shellac  to  a  cubic  foot  of  the  stone.  The 
shellac  is  added  to  give  an  early  strength  to  the  stone.  It  is  not 
certain  that  the  shellac  increases  the  ultimate  strength  of  the 
stone,  nor  is  it  certain  that  the  shellac  will  not  decay  and  prove  an 
element  of  weakness.  It  has  been  used  to  a  considerable  extent 
for  architectural  purposes  in  the  West.  It  is  not  entirely  sat- 
isfactory. 

Ransome  Stone. — This  stone  consists  of  sand  and  the  silicate 
of  soda.  One  bushel  of  sand  is  mixed  with  one  gallon  of  the 
silicate  of  soda  and  either  rammed  into  molds  or  rolled  into  slabs. 
At  this  stage  in  the  process  the  blocks  or  slabs  may  be  easily  cut 
into  any  desired  form.  They  are  then  immersed  under  pressure 
in  a  hot  solution  of  the  chloride  of  lime  until  they  become  satur- 
ated with  this  product.  They  are  then  drenched  with  cold  water 
to  wash  out  the  chloride  of  sodium  formed  during  the  operation. 


BUILDING    STONES   AND    CLAYS 


The  stone  is  used  for  grindstones  in  England  and  for  footpaths, 
etc. 

Artificial  Marble. — Gypsum  and  clay  are  made  into  a  paste 
with  gums  or  resins  so  that  the  surface  of  the  product  may  be 
highly  polished.  To  prevent  the  paste  from  setting  too  quickly  a 
little  sodium  silicate,  Na4SiO4,  is  added.  The  veins  are  made  by 
either  spreading  colors,  or  threads  of  silk  dipped  in  the  desired 


Fig.  306. — Type  of  building  as  built  for  the  city  of  New  York  by 
the  Board  of  Water  Supply.  H.  L.  Rogers,  architect.  Catskill 
aqueduct,  portion  of  the  new  water  system  for  city  of  New  York. 
This  brick  building  is  trimmed  with  Onondaga  litholite.  Photo, 
furnished  by  the  Onondaga  Litholite  Company,  Syracuse,  New  York. 


color,  on  a  smooth  non-absorbing  surface  and  pouring  the  mix- 
ture on  the  colors  or  threads.  The  product  is  then  remolded  and 
polished.  Pillars  and  columns  are  colored  by  wrapping  in  oil 
cloth,  oil  paper,  canvas,  etc.,  and  then  removing  and  polishing 
the  product. 


ARTIFICIAL    STONE 
CUT  CAST  STONE 


397 


Cut  Cast  Stone  is  manufactured  from  any  high  grade  natural 
stone,  preferably  a  granite  or  hard  marble.  It  is  crushed,  screened 
and  graded  to  six  different  sizes — the  largest  being  that  which 
will  pass  a  three-quarter  inch  screen.  A  very  small  proportion  of 
the  dust  is  used. 


Fig.  307. — New  York  State  Seal,  7  feet  and  6  inches  by  7  feet,  as 
manufactured  by  the  Onondaga  Litholite  Company  for  the  new 
armory  building  at  Ithaca,  New  York.  L.  H.  Pilcher,  State  Architect. 
By  courtesy  of  the  Onondaga  Litholite  Company. 

The  different  sizes  of  the  crushed  stone  are  weighed  carefully 
into  the  mixer;  the  Portland  cement  and  water  also  being  care- 
fully weighed,  thus  insuring  a  uniform  product. 

After  mixing,  the  material  is  poured  into  either  a  sand,  wood 
or  plaster  mold ;  a  portable  mixer,  with  which  the  liquid  concrete 


398 


BUILDING    STONBS   AND    CLAYS 


i  I,  i 


Fig.  80S.— First  Baptist  Church,  Syracuse,  New  York,  built  of  terra 
cotta.     Gordon  Wright,  architect.     Photo,  by  Smith  and  Holmes. 


ARTIFICIAL    STONE 


399 


is  kept  constantly  agitated,  being  used  to  convey  the  material 
from  the  mixer  to  the  molds.  An  electric  crane  is  used  for  this 
purpose.  This  portable  mixer  handles  two  yards  of  material  at 
one  time. 

After  removing  from  the  molds,  it  is  carefully  protected  from 
changes  in  temperature  and  draughts  for  five  days  longer,  after 
which  all  surfaces  are  carefully  recut  by  machinery  or  by  stone 
cutters.  At  least  one-quarter  of  an  inch  of  surface  material  is 


Fig.  309. — Atlantic  terra  cotta,  manufactured,  at  Perth  Amboy,  New 
Jersey.  By  courtesy  of  the  Atlantic  Terra  Cotta  Company. 

removed.  Any  texture  and  finish,  which  may  be  desired  and 
which  is  obtainable  in  natural  stone,  can  be  secured  in  this 
product. 

In  addition  to  this,  various  colors  and  combinations  are  pos- 
sible by  combining  different  colored  stones  in  the  mix  and  using 
mineral  colors  to  get  the  desired  effect.  A  jet  black  slag,  secured 
Jfrom  the  copper  refineries,  can  be  used  to  produce  a  stone  with 
strong  contrast  like  some  of  our  natural  granites. 


BUILDING    STONES    AND    CLAYS 


>> 

PQ 


ARTIFICIAL    STONE 


401 


The  absorption  of  this  manufactured  material,  after  it  is 
seasoned,  compares  very  favorably  with  that  of  the  natural  stones 
from  which  it  is  manufactured.  Only  a  very  small  percentage 
(about  1  per  cent)  of  the  weight  of  the  natural  stone  is  lost  in 
crushing  and  re-assembling  into  the  manufactured  article. 

This  material  has  been  coming  very  rapidly  into  use  in  the 
East  during  the  last  five  years.  The  Onondaga  Litholite  Com- 
pany of  Syracuse,  N.  Y.,  has  alone  furnished  this  stone  for  over 
four  hundred  large  and  prominent  structures  during  the  past  two 
years.  This  material  is  adapted  for  use  in  any  place  where  nat> 


Fig.  313. — Plant  No. 
Aniboy,  New  Jersey. 
Company. 


2  of  the  Atlantic  Terra  Cotta  Company,  Perth 
By    courtesy    of    the    Atlantic    Terra    Cotta 


ural  stone  can  be  used.  It  is  reasonably  low  in  price  and  it  is 
particularly  adapted  for  use  where  a  large  amount  of  ornamenta- 
tion is  desired.  (See  Fig.  306.) 

It  has  this  past  year  been  used  in  a  large  percentage  of  the 
public  buildings  erected  by  the  State  of  New  York,  as  well  as 
very  extensively  for  city  and  municipal  work  in  New  York  City 
and  throughout  the  state.  It  has  been  used  largely  in  the  con- 
struction of  balustrade  and  ornamental  garden  work,  as  well  as 
bridge  construction  and  in  a  number  of  high  grade  residences 
constructed  in  the  east.  (See  Fig.  307.) 
26 


402  BUILDING   STONES   AND    CLAYS 

ATLANTIC  TERRA  COTTA 

Atlantic  Architectural  Terra  Cotta  is  a  mixture  of  various 
clays  covered  with  a  color  spray  or  glaze,  and  burned  in  a  kiln 
at  a  temperature  closely  approximating  2250  degrees  Fahrenheit, 
the  kiln  is  known  as  a  closed  or  muffled  kiln  in  which  the  flames 
do  not  come  in  contact  with  the  material  but  pass  through  flues 
in  a  double  wall. 

A  covering  slip  or  glaze  makes  the  terra  cotta  practically  im- 
pervious and  unaffected  by  weather.  Firing  in  the  kiln  renders 
it  fireproof. 

The  economy  of  terra  cotta  lies  in  the  methods  of  manufacture 
which  depend  upon  the  plasticity  of  the  materials  used.  For 
plain  pieces,  such  as  ashlar  blocks  and  simple  modeled  courses,  a 
model  is  made  of  plaster  and  from  this  model  a  plaster  mold  is 
made.  The  plastic  terra  cotta  body  is  pressed  in  this  mold  and 
from  one  mold  a  great  many  pieces  may  be  pressed.  In  a  non- 
plastic  material,  such  as  stone,  every  piece  has  to  be  cut  or  carved 
separately  so  that  the  initial  cost  is  constant  for  every  piece.  The 
economy  of  modeling  and  molding  as  compared  to  cutting  and 
carving  is  apparent. 

In  modeled  pieces  the  model  is  made  of  clay  and  a  plastic  mold 
taken  from  the  clay  model.  It  frequently  happens  in  the  case  of 
intricate  modeling  that  the  work  can  be  executed  in  terra  cotta 
at  one-tenth  its  cost  in  natural  stone.  This  saving  is  particularly 
great  when  modeled  ornament  repeats  itself  frequently  as  it  does 
in  the  pinnacles  of  the  First  Baptist  Church,  Syracuse,  N.  Y. 
There  are  24,934  pieces  of  terra  cotta  in  this  church.  (See  Figs. 
308,  309,  310,  311,  312  and  313.) 


ARTIFICIAL    STONE  403 

REFERENCES 

Baker,  Ira  O.  A  Treatise  on  Masonry  Construction ;  John  Wiley 
and  Sons,  New  York,  1903. 

Baker,  Ira  O.  Roads  and  Pavements ;  John  Wiley  and  Sons, 
New  York,  1909. 

Butler,  D.  B.  Portland  Cement;  Its  Manufacture,  Testing  and 
Use.  Spon  and  Chamberlain,  London,  1906. 

Eckel,  E.  C.  Cements,  Limes  and  Plasters.  John  Wiley  and 
Sons,  New  York,  1907. 

Eckel,  E.  C.  The  Portland  Cement  Industry  from  a  Financial 
Standpoint.  Moody's  Magazine,  New  York,  1908. 

Grant,  John.  Portland  Cement ;  Its  Nature,  Tests  and  Uses.  E. 
and  F.  N.  Spon,  London,  1875. 

Jameson,  C.  D.  Portland  Cement,  Its  Manufacture  and  Use. 
D.  Van  Nostrand  Co.,  New  York,  1898. 

Lewis  and  Chandler.  Popular  Handbook  for  Cement  and  Con- 
crete Users.  N.  W.  Henley  Publishing  Company,  New 
York,  1911. 

Meade,  R.  K.  The  Examination  of  Portland  Cement.  The 
Chemcial  Publishing  Co.,  Easton,  Pa.,  1906. 

Radford,  H.  A.  Cement  and  How  to  Use  It.  The  Radford 
Architectural  Co.,  Chicago,  111.,  1910. 

Reid,  H.  A.  Concrete  and  Reinforced  Concrete  Construction. 
Myron  C.  Clark  Publishinug  Co.,  1908. 

Richards,  W.  A.,  and  North,  H.  B.  A  Manual  of  Cement  Test- 
ing. D.  Van  Nostrand  Co.,  New  York,  1912. 

Sabin,  L.  C.  Cement  and  Concrete.  McGraw-Hill  Publishing 
Co.,  New  York,  1905. 

Spaulding,  F.  P.  Hydraulic  Cement,  Its  Properties,  Testing  and 
Use.  John  Wiley  and  Sons,  New  York,  1906. 

Taylor  and  Thompson.  A  Treatise  on  Concrete,  Plain  and  Rein- 
forced. John  Wiley  and  Sons,  New  York,  1904. 


APPENDIX  I 

SOME  IMPORTANT  STRUCTURES  OF  THE 
UNITED  STATES 


LOCALITY 
Akron,  O  ........ 

Albany,  N.  Y.    .  .  . 

Albany,  N.  Y.    ... 

Allegheny,  Pa.   .  .  . 

Ashland,   Wis.    .  .  . 

Astoria,   Ore  ..... 

Atlanta,    Ga  ..... 

Baltimore,    Md.     . 
Baltimore,    Md.     . 
Baltimore,    Md.     . 
Bangor,    Me  ..... 

Boston,  Mass.    .  .  . 

Boston,   Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,   Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,   Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,  Mass.    .  .  . 

Boston,   Mass.    .  .  . 

Bridgeport,    Conn. 
Bridgeport,    Conn. 
Brooklyn,  N.  Y.    . 
Camden,  N.  J.   .  .  . 

Charlestown,  S.   C. 
Chicago,    111  ..... 

Chicago,    111  ..... 

Chicago,    111 
Chicago, 
Chicago, 
Cincinnati,   O.    ... 

Cleveland,    O.     ... 

Columbus,    O.    ... 

Columbus,    O.    ... 

Dayton,    O  ...... 

Dayton,    O  ......  , 

Denver,    Col  ..... 

Des  Moines,   la.    . 
Des  Moines,  la.    . 
Detroit,  Mich.    .  .  . 

Detroit,  Mich. 
Evansville,    Ind.    . 
Fort   Wayne,   Ind. 
Galesburg,    111.     .  . 
Hoboken,   N.    J. 
Houghton,   Mich.    , 
Indianapolis,    Ind. 
Jacksonville,   Fla. 
Jersey   City,   N.   J. 
Kansas  City,  Mo.    , 


111 
111 


STRUCTURE. 

.  Memorial  Chapel   

.  State    Capitol    

.City    Hall    

.Post  Office    

.Post   Office    

.  Custom   House   

.Court   House  and   Post   Office.... 
.Court   House  and   Post   Office.  .  .  . 

.City    Hall 

.  Peabody   Institute   

.Custom   House   and   Post   Office.. 

.  Custom    House    

.U.    S.    Court   House.. 

.Bunker     Hill     Monument 

.U.   S.   Post   Office    

.Herald    Building    

.Mass.    General    Hospital    

.Odd    Fellows'    Memorial    Hall.... 

.Hotel    Dartmouth    

.Hotel   Vendome    (old   part) 

.N.    Y.   Mut.   Life  Ins.    Bldg. 

.Voting   Men's   Christian  Union... 

.  Harvard     College     Buildings 

.Central    Congregational    Church.. 

.Chamber   of   Commerce 

.  South    Union    R.    R.    Station 

.  Post   Office    

.Bridgeport   Trust    Company 

.  Post   Office    

.  Cvistom   House   and    Post   Office.. 

.  Custom  House   

.  Court    House    

.  Chamber   of   Commerce 

.  Newberry    Library     

.  Rothschild    Building     

.  Insurance    Exchange    

.Chamber    of    Commerce 

.  City    Hall     

.Ohio    National    Bank 

.Court    House    and    Post    Office... 

.  Rike-Kumler   Building 

.  Post   Office 

.  State   Capitol    

.Court    House    and    Post    Office    .. 

.City    Hall     

.Court   House  and   Post   Office.... 

.City  Hall 

.Court  House  and   Post   Office.  .  .  . 
.Court  House  and   Post   Office.... 

.  Burlington   Station    

.Stevens    Institute    Building    

.State  Mining  School  Buildings.  .  . 

.  Court    House    

.Court  House  and   Post   Office.... 

.  Court    House    

.Court  House  and   Post   Office.. 


Lansing,  Mich.  . 
Lidgerwood,  N.  D. 
Little  Rock,  Ark. 
Lowell,  Mass.  .  .  . 
Madison,  Wis.  .  . 
Memphis,  Tenn.  . 


.State   Capitol    

.First    National    Bank 

.Court   House  and   Post   Office.  . 

.Post  Office    

.Wisconsin   State  Capitol    

.Union    Station    

404 


MATERIAL. 
..Sandstone,    Marietta,    O. 
..Granite,   Hallowell,   Me. 
.  .  Granite,  Milford,  Mass. 
.  .  Granite,   Hallowell,   Me. 
..Sandstone,   Houghton,   Wis. 
.  .  Sandstone,  near  Astoria. 
..Granite,   Barre,  Vt. 
..Granite,   Cape  Ann,   Mass. 
..Marble,  Texas    and     Cockeysville,    Md. 
..Marble,  Texas    and     Cockeysville,    Md. 
..Granite,   Frankfort,   Me. 
.  .  Granite,   Quincy,  Mass. 
.  .  Granite,   Quincy,   Mass. 
..Granite,   Quincy,  Mass. 
.  .  Granite,   Cape  Ann,   Mass. 
.  .  Granite,   Concord,   N.    H. 
..Granite,   Westford,  Mass. 
..Granite,   Hallowell,   Me. 
..Marble,   Rutland,  Vt. 
.  .Marble,   Italy. 
..Marble.   Tuckahoe,   N.   Y. 
.  .  Sandstone,   Bay  View,   New   Brunswick. 
..Sandstone,  Amherst,   O. 
.  .  Conglomerate,    Roxbury,    Mass. 
..Granite,   Milford,   Mass. 
.  .  Granite.   Stony    Creek,    Conn. 
..Sandstone,   Middlesex   Co.,   Conn. 
.  .  Granite,   Woodbury,   Vt. 
.  .  Granite,   Vinalhaven,  Me. 
.  -Marble,   Proctor,   Vt. 

..Marble,   Hastings   and   Tuckahoe,    N.  \ .. 
..Dolomite,   Leinont,   111. 
.  .  Granite,   Fox  Island  and  Hallowell,  Me. 
..Granite,   Stony    Creek,    Conn. 
..Granite,   Woodbury,   Vt. 
..Granite,   Woodbury,   Vt. 
.  .  Granite,   Milford,   Mass. 
..Granite,   Woodbury,   Vt. 
.  .  Granite,   Woodbury.   Vt. 
..Sandstone.   Berea,   O. 
..Granite,   Woodbury,   Vt. 
..Sandstone,   Berea,   O. 
..Granite,   Gunnison,   Col. 
..Limestone,   Keokuk   and  Joliet,   111. 
.  .  Granite,   Woodbury,   Vt. 
.  .  Limestone,   Bedford,   Ind. 
..Granite,   Bethel,   Vt. 
..Limestone,   Bedford,   Ind. 
..Sandstone,   Sand   Point,   Mich. 
.  .  Granite,   Woodbury,  Vt. 
.  .  Diabase,    Jersey    City,    N.    J. 
..Sandstone,   Portage   Entry,   Mich. 
.-Limestone,   Bedford,   Ind. 
.  .  Marble,   Georgia. 
.  .  Diabase,    Jersey    City,    N.    J. 
..Granite,    South    Park,    Col.,    and    Llano 
C-  ,   Texas. 

•  •Sandstone.   Amherst,   O. 
.  -  Granite,   Woodbury,   Vt. 

•  -Sandstone,   Berea,   O. 

•  •Granite,   Deer  Island,   Me. 
.  .  Granite,   Bethel,   Vt. 

•  •Granite,  Woodbury,  Vt. 


SOME    IMPORTANT   STRUCTURES 


405 


Middletown,  Conn.  . 
Milwaukee,  Wis.  .  .  . 
Milwaukee,  Wis.  .  .  . 
Minneapolis,  Minn.. 

Mobile,    Ala 

Montpelier,    Vt. 
Montpelier,    Vt.     .  .  . 

Newark,    N.   J 

New  Haven,  Conn.  . 
New  Haven,  Conn.  . 
New  Orleans,  La... 
New  York,  N.  Y... 
New  York,  N.  Y. .  . 
New  York,  N.  Y. .  . 
New  York,  N.  Y... 
New  York,  N.  Y... 

New  York,  N.  Y... 
New  York,  N.  Y... 

Norfolk,    Va 

Olean,    N.    Y 

Pensacola,    Fla.     . .  . 

Peoria,    111 

Philadelphia,    Pa.    .  . 
Philadelphia,   Pa.    .  . 
Pittsburgh,    Pa.     .  . . 
Pittsburgh,    Pa. 
Providence,  R.  I.... 

Providence,  R.  I.... 

Quincy,   111 

Raleigh,   N.   C 

Rochester,  N.  Y.  .. 
Rochester,  N.  Y.  .. 

Rockford,    111 

San  Jose,    Cal 

Savannah,  Ga 

Scranton,    Pa 

Sioux   Falls,    S.    D. . 

Springfield,  111 

Springfield,  Mass.  . 
St.  Augustine,  Fla.. 
Stanford  Univ.,  Cal, 
Syracuse,  N.  Y.  ... 
Syracuse,  N.  Y.  ... 
Syracuse,  N.  Y.  ... 

Trenton,   N.  J 

Trenton,   N.  J 

Warren,    O 

Washington,  D.  C.. 
Washington,  D.  C. . 
Washington,  D.  C.. 
Washington,  D.  C.. 
Washington,  D.  C. . 
Washington,  D.  C.. 
Washington,  D.  C.. 

Wichita,  Kan 

Wilmington,  N.  C. . 
Worcester,  Mass.  . 
Youngstown,  O.  .  . . 
Youngstown,  O.  ... 


.Wesleyan    University    Buildings.  ...  Sandstone,   Portland,   Conn. 

.Court  House,  Custom  House,  P.   O. Granite,   Frankfort,   Me. 

.N'thw't'n.   Mut.   Life  ins.   Co.   Bldg.Granite,   Wpodbury.   Vt. 

.Univ.    of    Min.    Buildings Dolomitic  limestone,  Minneapolis,  Minn 

.  Custom    House    Granite,  Quincy,  Mass. 

.  State   Capitol    Granite,  Barre,  Vt. 

.  Post    Office     Marble,  Proctor,  Vt. 

.Custom  House  and   Post   Office.  ..  .Sandstone,   Belleville,  N.  J. 

.National    Savings    Bank Granite,   Woodbury,  Vt. 

.  Osborn    Memorial    Hall Granite,  Stony  Creek,  Conn. 

.  Custom  House Granite,  Ouincy,  Mass. 

.Metropolitan    Museum    of    Art Granite,   Mt.   Desert,  Me. 

.New  York  City  Post  Office Granite,  Dix  Island,  Me. 

.  Astor    House    Granite,   Quincy,   Mass. 

.Obelisk  in  Central   Park Hornblende  Granite,   Egypt. 

.Library    of   Columbia   University ...  Granite,  Stony    Creek,   Conn.,  and  Mil- 
ford,  Mass. 

.Bankers    Trust    Co.    Building Granite,   Woodbury,  Vt. 

.Western  Union   Tel.    Bldg Granite,  Bethel,  Vt. 

.  Fergus   Reid   Building Granite,  Woodbury,  Vt. 

.  First    National    Bank Granite,   Woodbury,  Vt. 

.Court  House  and  Post  Office Limestone,  Bowling  Green,  Ky. 

.Court  House  and  Post  Office Sandstone,  Amherst,  O. 

.Custom    House    Marble,  Montgomery  Co.,  Pa. 

.Univ.   of  Pa.   Buildings Serpentine,   Chester  Co.,   Pa. 

.Court  House  and  Post  Office Granite,  E.  Blue  Hill,  Me. 

.  Pittsburgh   Bank    Granite,  Troy,   N.   H. 

.  City  Hall Granite,   Hurricane    Island,    Me. ;    Wes- 
terly, R.  I.,  and  Concord,  N.  H. 

.Turk's  Head  Building Granite,  Bethel,  Vt. 

.Court  House  and  Post  Office Limestone,  Bedford,  Ind. 

.Court  House  and  Post  Office Granite,   Goldsboro,  N.   C. 

.Custom   House  and   Post  Office Sandstone,  Portland,  Conn. 

.Union  Trust  Company's  Building.  .Granite,  Bethel,  Vt. 

.  Post  Office    Sandstone,  Portage,  Mich. 

.  Post   Office    Sandstone,  San  Jose,  Cal. 

.Court  House  and  Post  Office Marble,  Pickens  Co.,  Ga. 

.  Post   Office    Granite,  Hurricane  Island,  Me. 

.Court   House  and  Post  Office Quartzite,  E.   Sioux  Falls,  S.   D. 

.  Post  Office    • Limestone,  Nauvoo,  111. 

.  Post  Office    Sandstone,  Long  Meadow,  Mass. 

.Court  House  and  Post  Office Coquina,  St.  Augustine,  Fla. 

.University    Buildings    Sandstone,  Santa  Clara  Co.,  Cal. 

.Fine  Arts   Buildings   S.   U Sandstone,  E.  Long  Meadow,  Mass. 

.Hall   of  Languages   S.  U Limestone,  Syracuse,  N.  Y. 

.Jewish    Synagogue    Limestone,  Bedford,  Ind. 

.  State   Capitol    Sandstone,  Trenton,  N.  J. 

.Custom   House  and  Post   Office.  ..  .Sandstone,  Amherst,  O. 

.Western  Reserve  Bank Granite,  Woodbury,  Vt. 

.  Post  Office    Granite,  Vinalhaven,  Me. 

.New  Post  Office    Granite,  Bethel,  Vt. 

.New   Corcoran  Art   Gallery Marble,  Pickens  Co.,  Ga. 

.New    Public   Library Marble,  Proctor,  Vt. 

.Smithsonian    Institution    Sandstone,  Seneca  Creek,  Md. 

.Union   Station    Granite,  Bethel,  Vt. 

.Congressional  Library  Building Granite,  Concord,  N.  H. 

.Court  House  and  Post  Office Limestone,  Bedford,  Ind. 

.Court  House  and  Post  Office Sandstone,  Sanford,  N.   C. 

.  City    Hall    Granite,  Milford,  Mass. 

•City    Hall    Granite,  Woodbury,  Vt. 

.Mahoning  County  Court  House.  ..  .Granite,  Woodbury,  Vt. 


APPENDIX  II 

GLOSSARY 

Accessory  Mineral, — One  not  necessary  to  the  definition  of  a 
rock  but  which  sometimes  determines  the  variety. 

Acid. — A  term  applied  to  the  igneous  rocks  containing  a  high 
percentage  of  silica. 

Adobe  Brick. — A  sunbaked  brick  manufactured  from  a  sandy 
or  calcareous  clay  and  used  extensively  in  warm  climates. 

Air  Brick. — A  hollow  or  pieced  brick  built  into  a  wall  to  allow 
the  passage  of  air. 

Air  Shrinkage. — The  decrease  in  volume  which  a  clay  under- 
goes when  dried  in  the  air. 

Alabaster. — A  white,  massive  variety  of  gypsum.  When  pol- 
ished it  often  resembles  some  clouded  stalagmites. 

Alum  Shales. — Shales  bearing  alum  formed  by  the  decomposi- 
tion of  pyrite. 

Amphibole. — The  name  for  a  group  of  related  minerals  which 
are  essentially  silicates  of  aluminum,  magnesium,  calcium  and 
iron,  and  whose  cleavage  angles  are  approximately  56  and  124 
degrees. 

Andesite. — An  eruptive  rock  whose  mineral  composition  is 
plagioclase  and  hornblende  or  augite. 

Anhydrite. — A  mineral  which  in  composition  is  calcium  sul- 
phate and  which  absorbs  moisture  from  the  atmosphere  when 
used  in  base  courses  as  a  substitute  for  marble. 

Ankerite. — An  objectionable  calcium,  magnesium  and  iron  car- 
bonate sometimes  found  in  calcareous  rocks. 

Anorthite. — A  calcium  feldspar  often  present  in  diabase. 

Anorthosite. — A  granular  irruptive  rock  consisting  essentially 
of  labradorite. 

Anticline. — The  arch  part  of  a  folded  bed. 

Anticlinorium. — A  mountain  mass  arch  shaped  in  its  general 
internal  structure. 

Apatite. — An  accessory  mineral  sometimes  occurring  in  gran- 
ites. It  is  a  calcium  phosphate. 

Aplite. — A  fine  grained  granite  consisting  of  quartz  and  feld- 
spar. Muscovite  may  be  sparingly  present.  The  outcrop  usually 
occurs  as  a  dike. 

406 


GLOSSARY  407 

Aragonite. — A  mineral  having  the  same  composition  as  calcite 
but  crystallizing  in  the  orthorhombic  system. 

Arch  Brick. — A  term  commonly  applied  to  brick  taken  from 
the  arches  of  a  kiln.  They  are  usually  overburned. 

Argillaceous. — A  term  applied  to  limestones  and  sandstones 
containing  clayey  matter. 

Argillite. — An  argillaceous  schist  or  clay  slate  which  breaks 
readily  into  thin  slabs. 

Arkose. — A  variety  of  sandstone  containing  an  appreciable 
quantity  of  feldspars. 

Asbestos. — A  term  often  applied  to  fibrous  varieties  of  amphi- 
bole  or  serpentine  used  in  fireproofing. 

Ashlar  Brick. — A  term  often  applied  to  brick  which  have  one 
edge  chiseled  so  as  to  resemble  rock-faced  stone. 

An  git  e. — An  aluminous  pyroxene,  the  commonest  species  of 
the  pyroxene  group. 

Authigenous. — Minerals  originating  chemically  within  a  rock 
mass. 

Ball  Clay. — A  white  burning  clay  used  as  a  bond  in  the  manu- 
facture of  china  ware. 

Basalt. — A  basic  igneous  rock  consisting  of  plagioclase  and 
augite.  Olivine  is  a  common  constituent. 

Basic. — A  term  applied  to  igneous  rocks  high  in  bases  and  low 
in  their  silica  content. 

Bastard  Granite. — A  term  often  applied  by  quarrymen  to 
granite  gneisses. 

Bed. — A  continuous  mass  of  material  deposited  under  water 
at  about  the  same  time. 

Bio  tit  e. — A  mineral  of  the  mica  family.  It  is  essentially  a 
silicate  of  aluminum,  magnesium  and  iron.  It  is  often  called  the 
black  mica,  the  iron  mica  or  the  magnesium  mica. 

Black  Coring. — The  development  of  a  black  core  in  brick  due 
to  improper  burning. 

Blind  Joint. — An  obscure  bedding  plane. 

Bluestone. — In  New  York  this  term  is  applied  to  the  bluish 
gray  sandstones.  In  the  District  of  Columbia  it  is  applied  to  a 
mica  schist.  In  Maryland  it  is  applied  to  a  gray  gneiss. 

Boss. — A  dome-like  mass  of  igneous  rock,  standing  above  the 
surrounding  country. 

Bottom  Joint. — A  joint  or  bedding  plane  in  a  horizontal  or 
nearly  horizontal  position. 

Boulder  Quarry. — A  term  often  applied  in  Vermont  to  a 
granite  quarry  confined  to  a  group  of  large  boulders.  It  may  be 


408  BUILDING    STONES   AND    CLAYS 

applied  to  any  granite  quarry  where  the  stone  is  naturally  broken 
up  by  joints  into  comparatively  small  blocks. 

Breccia. — A  rock  made  up  of  angular  fragments  produced  by 
crushing  and  then  recemented  by  infiltrating  mineral  matter. 

Brecciated. — A  term  applied  to  angular  fragments  that  have 
not  been  transported  from  the  place  where  they  were  fractured. 

Brick  Clay. — Any  clay  that  can  be  used  in  the  manufacture  of 
brick. 

Brownstone. — A  term  formerly  applied  to  the  brown  sand- 
stones but  now  somewhat  loosely  used. 

Calcareous. — Containing  calcium  carbonate. 

Calcareous  Tufa. — A  porous  mass  of  calcium  carbonate,  de- 
posited on  rock  ledges,  in  swamps,  on  plants  and  around  the 
mouth  of  springs. 

Calcite. — A  mineral  consisting  of  calcium  carbonate  but  crystal- 
lizing in  the  hexagonal  system.  Its  cleavage  is  rhomohedral,  and 
perfect. 

Cellular. — A  term  often  applied  to  basalts  containing  cells  or 
cavities. 

Chalk. — A  soft  limestone  with  earthy  texture  and  normally 
white  color. 

Chert. — A  cryptocrystalline  variety  of  quartz.  The  term  is 
often  applied  to  hornstone  and  to  any  impure  flinty  rock. 

China  Clay. — Any  clay  suitable  for  the  manufacture  of  china 
ware. 

Chlorite. — A  group  name  for  the  greenish  colored  micaceous 
minerals.  They  are  silicates  of  aluminum  with  magnesium  and 
iron.  A  secondary  mineral  derived  from  the  alteration  of 
pyroxene,  amphibole,  biotite  and  vesuvianite. 

Clastic. — A  rock  consisting  of  rock  or  mineral  fragments  de- 
rived from  other  rocks. 

Clay. — A  fine  textured  unconsolidated  rock  having  a  certain 
amount  of  plasticity  when  wet  but  hardening  when  burned. 

Cleavage. — The  natural  parting  of  a  mineral  due  to  cohesion. 
The  property  of  metamorphic  rocks  to  split  in  certain  definite 
directions. 

Clinker  Brick. — A  very  hard  burned  brick. 

Conchoidal  Fracture. — A  term  applied  to  the  break  of  quartz, 
certain  other  minerals  and  compact  rocks  whose  broken  surfaces 
show  concentric  rings. 

Concretionary. — Made  up  of  rounded  aggregations  of  mineral 
matter. 

Concretion. — A  rounded  body  of  mineral  matter  as  chert  in 


GLOSSARY  409 

limestone  or  as  calcium  carbonate  or  iron  carbonate  in  certain 
clays  and  shales. 

Conglomerate. — A  rock  mass  composed  chiefly  of  rounded 
fragments.  Such  rocks  are  sometimes  called  pudding  stone.  The 
term  conglomerate  often  includes  the  breccias. 

Coquina. — A  limestone  composed  of  loosely  cohering  shell 
fragments  cemented  together  by  an  infiltration  of  the  carbonate 
of  lime. 

Coral  Limestone. — Any  rock  mass  composed  of  the  broken 
fragments  of  coral. 

Cryptocrystalline. — A  term  applied  to  the  varieties  of  quartz 
that  are  finely  crystalline,  and  to  some  igneous  rocks. 

Crystalline  Rocks. — A  term  applied  to  the  metamorphic  rocks 
composed  of  crystalline  mineral  grains. 

Cutoff. — The  direction  along  which  granite  must  be  channeled 
when  it  will  not  split  in  that  direction. 

Decomposition.— T-hz  breaking  down  of  a  rock  through  the 
agents  of  weathering. 

Diabase. — A  basic  igneous  rock  consisting  essentially  of  plagi- 
oclase,  augite  and  magnetite.  Olivine  may  be  present.  It  in- 
cludes most  trap  rocks. 

Diagonal  Joints. — Joints  diagonal  to  the  strike  of  the  cleavage 
in  slate. 

Diallage. — A  thin  ^foii^ted^j^ariety  of  pyroxene  present  in 
many  gobbros. 

Differentiation. — The  process  of  the  separation  of  a  molten 
solution  into  portions  which  form  rocks  physically  or  chemically 
unlike. 

Dike. — A  long  and  relatively  narrow  body  of  igneous  rock 
filling  a  fissure  at  the  time  it  was  formed. 

Dimension  Stone. — Stone  quarried  and  cut  of  required  size. 

Diorite. — A  basic  igneous  rock  consisting  of  plagioclase,  usually 
andesine,  and  hornblende.  It  is  often  porphyritic. 

Diorite  Porphyry. — A  basis  igneous  porphyritic  rock  of  the 
same  mineral  composition  as  diorite. 

Dip. — The  degree  and  the  direction  of  the  inclination  of  a 
bed,  cleavage  plane,  joint,  etc. 

Disintegration. — A  term  applied  to  the  mechanical  breaking 
down  of  a  rock  on  weathering. 

Dolerite. — A  coarsely  crystalline  variety  of  basalt. 

Dolomite. — A  mineral  consisting  of  the  double  carbonates  of 
calcium  and  magnesium.  Also  a  rock  made  up  chiefly  of  the 
mineral  dolomite. 


410  BUILDING    STONES   AND    CLAYS 

Doivn-Draft  Kiln. — One  in  which  the  heat  enters  the  kiln 
chamber  from  the  top  and  passes  down  through  the  ware. 

Dry. — A  seam  in  a  stone,  usually  invisible  in  the  freshly 
quarried  rock,  but  which  may  open  up  in  cutting  or  on  exposure 
to  the  atmosphere. 

Dryer  White. — A  white  scum  which  often  forms  on  bricks 
during  the  process  of  drying. 

Dry  Pan. — A  revolving  pan  used  for  grinding  dry  clays.  Its 
bottom  is  perforated. 

Dry-Press  Process. — A  method  of  manufacturing  clay  products 
from  slightly  moistened  clay  by  pulverizing  and  pressing  them 
into  steel  dies. 

Dust  Pressed. — Synonymous  with  dry  pressed  but  usually 
applied  to  the  manufacture  of  wall  tile. 

Enameled  Brick. — Brick  which  are  coated  on  one  or  more  sur- 
faces with  a  white  or  colored  enamel. 

Encaustic  Tile. — A  term  applied  to  floor  tile  which  has  a  sur- 
face pattern  of  one  type  of  clay  and  a  backing  of  a  different 
type. 

End  Joint. — A  vertical  joint  about  parallel  to  the  direction  of 
the  cleavage  dip. 

Epidote. — A  peculiar  yellowish-green  mineral  sometimes 
occurring  in  granites.  In  composition  it  is  a  silicate  of  calcium, 
aluminum  and  iron. 

Erosion. — The  wearing  away  of  a  rock  surface  by  mechanical 
and  chemical  agencies. 

Essential  Minerals. — Those  necessary  to  the  definition  of  a 
rock. 

Eruptive. — Igneous  rocks  that  have  been  extruded. 

Extrusive. — Igneous  rocks  which  have  cooled  after  reaching 
the  surface. 

False  Cleavage. — A  secondary  slip  cleavage  superinduced  on 
slaty  cleavage. 

Fault. — A  dislocation  caused  by  a  slipping  of  rock  masses  along 
some  plane  of  fracture.  Also  the  dislocated  structure  resulting 
from  such  slipping. 

Feldspar. — A  name  applied  to  a  group  of  minerals  possessing 
several  characteristics  in  common.  They  are  silicates  of  alum- 
inum with  potassium,  or  sodium,  or  both,  or  with  calcium,  or 
sodium  and  calcium.  Iron  and  manganese  are  absent.  Their 
cleavage  is  perfect. 

Felsite. — A  cryptocrystalline  mixture  of  quartz  and  feldspar. 
The  ground  mass  of  the  quartz  porphyries. 

Felspathoid. — A  group  of  minerals  that  may  replace  the  feld- 


GLOSSARY  411 

spars  in  the  formation  of  igneous  rocks.     Leucite,  nephelite  and 
sodalite  are  the  most  common. 

Femic. — A  term  applied  to  rocks  rich  in  iron  and  magnesium. 

Ferruginous. — Containing  either  the  anhydrous  or  hydrous 
oxides  of  iron. 

Ferromagnesian. — A  term  applied  to  the  dark  colored  silicates 
which  contain  both  iron  and  magnesium. 

Fire  Clay. — A  very  refractory  clay  used  in  the  manufacture  of 
fire  brick  and  crucibles. 

Fireproofing. — A  name  applied  to  products  used  in  floor  arches, 
partitions,  etc.,  to  render  a  building  fireproof. 

Fire  Shrinkage. — The  decrease  in  volume  which  a  clay  under- 
goes during  the  process  of  burning. 

Fissility. — The  tendency  shown  in  slate  to  separate  into  thin 
laminae. 

Flagstone. — A  term  applied  to  sandstones  which  split  readily 
into  blocks  suitable  for  flagging  purposes. 

Flashed  Brick. — A  term  applied  to  brick  whose  edges  have 
been  darkened  or  rendered  spotted  by  special  treatment  in  their 
manufacture. 

Flint. — A  cryptocrystalline  variety  of  quartz,  breaking  with  a 
deep  conchoidal  fracture  and  a  sharp  cutting  edge.  Also  a  term 
applied  to  quartz  veins  and  beds  of  quartzite  in  slate. 

Flue  Linings.- — Cylindrical  or  rectangular  pipes  used  for  lining 
flues. 

Flow  Structure. — A  banding  produced  in  many  igneous  rocks 
by  a  flowage  of  the  mass  while  soft. 

Fluorite. — A  mineral  consisting  of  calcium  fluoride. 

Foliation. — The  arrangement  of  the  minerals  in  a  crystalline 
rock  in  parallel  layers. 

Forest  Marble. — An  argillaceous  limestone  in  which  the  color- 
ing matter  is  so  distributed  as  to  resemble  landscapes. 

Formation. — A  mapable  area  of  beds  possessing  common  and 
general  characteristics. 

Fossiliferous. — Containing  any  record  of  an  organism  pre- 
served in  the  crust  of  the  earth. 

Freestone. — A  term  applied  to  any  stone  that  will  work  easily 
and  freely  in  any  direction. 

Furring  Brick. — Hollow  brick  used  for  lining  the  inside  of  a 
wall. 

Gabbro. — A  basic  igneous  rock  consisting  of  plagioclase, 
usually  labradorite,  and  a  pyroxene,  usually  augite  or  diallage. 
Magnetite  is  often  present  and  some  varieties  bear  olivine. 

Garnet. — A  silicate  of  aluminum,  calcium,  iron  or  magnesium, 


412  BUILDING    STONES   AND    CLAYS 

which  crystallizes  in  the  isometric  system.  The  common  garnet 
in  metamorphic  limestones  is  grossularite.  The  one  in  mica 
schists  is  almandine. 

Gneiss. — A  metamorphosed  igneous  rock  having  its  ferromag- 
nesian  minerals  arranged  in  more  or  less  massive  bands  or  layers. 
Also  a  metamorphosed  highly  feldspathic  sedimentary  rock. 

Gneiss  old  Granite. — Having  a  structure  somewhat  resembling 
a  gneiss. 

Grain. — An  obscure  vertical  cleavage  more  or  less  parallel  to 
the  end  or  dip  joints. 

Granite  Porphyry. — An  igneous  rock  with  the  same  mineral 
composition  as  granite,  but  with  a  porphyritic  texture. 

Granitoid. — Having  a  texture  like  that  of  granite. 

Granodiorite. — A  diorite  bearing  an  appreciable  amount  of 
quartz. 

Graphite. — A  soft  metallic,  dark  steel  gray  mineral  consisting 
of  carbon. 

Gravel. — Small  stones  or  fragments  of  stones. 

Graywackc. — A  compact  sandstone  consisting  of  quartz,  feld- 
spars and  argillaceous  matter. 

Greenstone. — An  indefinite  term  often  applied  to  the  basic 
igneous  rocks  of  greenish  color  due  to  the  presence  of  chlorite. 

Grit. — A  term  applied  to  sandstones  when  suitable  for  whet- 
stones. 

Grog. — Pulverized  burned  clay  or  brick  which  is  often  added 
to  the  raw  clay  mixture  to  decrease  the  shrinkage  and  density  of 
the  burned  ware. 

Gumbo. — A  term  applied  to  the  soils  which  yield  a  sticky  mud 
when  wet.  This  is  characteristic  of  the  mud  of  the  prairies. 

Gypsum. — A  hydrous  calcium  sulphate  which  is  2  in  the  scale 
of  hardness. 

Hardness. — The  power  of  a  mineral  to  resist  abrasion.  The 
scale  of  hardness  varies  from  1  to  10. 

Hardpan.—A  layer  of  hard  detritus  under  soft  soil. 

Hardway. — A  direction  of  splitting  at  right  angles  to  the  rift 
and  grain. 

HCl. — Hydrochloric  or  muriatic  acid. 

Header. — A  brick  or  stone  laid  with  its  longer  axis  at  right 
angles  to  the  surface  of  the  wall. 

Heading. — A  term  often  applied  by  quarrymen  to  a  group  of 
close  joints. 

Hematite. — An  anhyrous  oxide  of  iron  whose  fine  powder  is 
of  cherry  red  or  blood  red  color. 


GLOSSARY  413 

Hip. — A  piece  of  roofing  tile  required  where  a  hip  starts  from 
a  ridge. 

Hip-Roll. — A  tile  used  for  covering  the  hips  on  roofs. 

Hip-Tile. — Tile  which  run  up  against  a  hip  stringer. 

HNOS.— Nitric  acid. 

Hogback. — Shear  zones. 

Hollozv  Blocks. — These  are  usually  rectangular  in  form  and 
hollow.  They  are  used  in  exterior  walls  and  partitions. 

Hollow  Brick. — Brick  molded  with  hollow  spaces  in  them,  and 
strengthened  by  cross  webs. 

Holo crystalline. — A  term  applied  to  rocks  wholly  composed  of 
crystalline  constituents. 

Hygroscopic. — The  ability  of  a  rock  or  chemical  compound  to 
absorb  or  condense  moisture  from  the  atmosphere. 

Hypersthcne. — A  mineral  of  the  pyroxene  group  present  in 
norite. 

Iceland  Spar. — A  popular  name  for  transparent  calcite  used 
for  polarizing  light. 

Igneous  Rocks. — Rocks  formed  by  the  action  of  heat  with 
sufficient  intensity  to  effect  fusion. 

Inclusions. — Fragments  of  one  kind  of  rock  inclosed  in  another 
type  of  rock. 

Interlocking  tile. — Roofing  tile  with  edges  and  grooves  which 
interlock  when  the  tile  are  laid  on  the  roof. 

Irruptive. — A  term  used  to  denote  the  igneous  rocks  that  have 
worked  their  way  upward  from  the  zone  of  flowage  through 
other  rocks  but  have  not  flowed  out  over  the  surface. 

Isoclinal. — A  fold  with  sides  nearly  parallel. 

Itacolumyte. — A  friable  and  flexible  sandstone,  especially  when 
in  thin  slabs.  Its  flexibility  is  due  to  the  interlocking  of  the 
quartz  grains. 

Jasper. — A  cryptocrystalline  variety  of  quartz,  usually  red  or 
brown  in  color.  A  term  applied  also  to  the  marbles  of  Vermont 
which  in  color  closely  resemble  the  mineral  jasper. 

Joints. — Fractures  which  may  occur  in  any  kind  of  rock.  In 
position  they  vary  from  horizontal  to  vertical.  When  horizontal 
in  granite  they  develop  a  sheeted  structure. 

Kaolin. — A  white  residual  clay  assuming  rock  proportions  and 
used  in  the  manufacture  of  wall  tile,  china  ware  and  sanitary 
ware. 

Kao  Unite. — A  mineral  which  is  a  hydrous  silicate  of  aluminum 
resulting  from  the  decomposition  of  feldspars. 

Kiln  White. — A  scum  which  often  appears  in  the  burning  of 
brick. 


414  BUILDING    STONES   AND    CLAYS 

Knots. — A  term  applied  to  the  concretions  sometimes  found  in 
granites  and  gneisses.  Also  to  the  concretions  present  in  sedi- 
mentary rocks. 

Labrador  lie. — A  mineral  of  the  feldspar  group,  usually  gray  in 
color,  crystallizing  in  the  triclinic  system,  and  with  cleavage 
planes  finely  striated. 

Lava. — Molten  material  poured  out  from  a  volcano.  Molten 
rock  intruded  subterraneously  between  strata.  It  is  applied  also 
to  the  same  material  after  it  has  cooled. 

Ledge. — A  term  applied  to  a  single  bed  or  to  a  group  of  beds 
occurring  in  a  quarry.  Also  to  any  outcrop  of  rock  on  the 
surface. 

Lift. — A  name  often  applied  by  quarrymen  to  joint  planes 
which  are  approximately  in  horizontal  position. 

Limestone. — A  rock  mass  consisting  of  calcium  carbonate, 
which  through  metamorphism  passes  into  a  marble. 

Limonite. — A  brown  or  yellow  mineral  which  chemically  is  a 
hydrous  oxide  of  iron,  2Fe2O3,  3H2O. 

Liparite. — A  lava  rich  in  silica,  especially  abundant  in  the 
Lipari  Islands. 

Loess. — A  pale,  yellowish,  homogeneous,  calcareous  clay,  loam 
or  sand  of  Pleistocene  age. 

Luster.— The  quality  and  quantity  of  light  reflected  by  a 
mineral. 

Magma. — The  molten  material  from  which  the  igneous  rocks 
are  formed. 

Magnesite. — A  white  to  brown  magnesium  carbonate  crystal- 
lizing in  the  hexagonal  system.  It  is  often  found  massive. 

Magnetite. — A  black  iron  oxide  which  is  strongly  magnetic 
both  before  and  after  heating.  It  crystallizes  in  regular  octahe- 
drons. 

Mantle-Rock. — The  loose  fragmental  material  that  results  from 
the  disintegration  of  both  igneous  and  sedimentary  rocks. 

Marble. — A  metamorphosed  limestone  or  dolomite.  A  massive 
variety  of  calcite  which  is  capable  of  being  polished  and  used 
for  architectural  and  ornamental  purposes. 

Marcasite. — A  white  iron  pyrite  which  crystallizes  in  the 
orthorhombic  system.  It  is  more  readily  decomposed  than  the 
other  sulphides  of  iron. 

Matrix. — A  term  used  for  the  unindividualized  material  in 
igneous  rocks.  Also  the  chief  substance  of  a  slate  itself. 

Matt  Glaze. — A  dull  glaze  applied  to  some  clay  products. 

Melaphvre. — A  term  applied  to  any  igneous  porphyry  with  a 
dark  ground  mass. 


GLOSSARY  415 

Metamorphism. — The  process  by  which  a  rock  is  altered  in  the 
molecular  structure  of  its  minerals  and  in  their  arrangement. 

Mexican  Tile. — A  term  applied  to  roofiing  tile  with  semi- 
circular cross  section. 

Mica. — The  name  of  a  group  of  minerals  with  eminent  basal 
cleavage.  They  are  essentially  hydrous  silicates  of  aluminum 
with  potassium,  magnesium  and  iron.  Sodium  and  lithium  micas 
are  well  known. 

Micaceous  Sandstone.— One  containing  many  scales  of  mica. 

Microcline. — A  potassium,  aluminum  silicate  of  the  feldspar 
group,  crystallizing  in  the  triclinic  system.  It  frequently  occurs 
in  granite. 

Mineral. — A  natural  inorganic  element  or  compound  with 
theoretically  a  definite  chemical  composition,  and  usually  a 
definite  crystalline  form. 

Molded  Brick. — A  term  often  applied  to  soft-mud  brick. 

Monocline. — An  abrupt  downward  folding  of  nearly  horizontal 
strata,  without  any  corresponding  bend  to  form  an  anticline  or 
syncline. 

Monsonite. — A  rock  which  is  intermediate  in  mineral  composi- 
tion between  a  syenite  and  a  diorite. 

Muscovite. — The  common  potassium  member  of  the  mica 
group.  It  is  often  called  the  white  mica.  Also  the  potassium 
mica. 

Nephelite. — A  silicate  of  aluminum,  sodium  and  potassium 
which  crystallizes  in  the  hexagonal  system  and  occurs  as  small 
crystals  or  grains  in  the  intermediate  igneous  rocks.  The  variety 
eleolite  is  distinguished  by  its  greasy  luster. 

Norman  Tile. — A  brick  with  dimensions  of  12  by  2l/±  to  2l/2 
inches. 

Novaculite. — An  exceedingly  fine  grained  sandstone,  abundant 
in  Arkansas,  and  used  for  hones  and  whetstones. 

Obsidian. — A  common  name  for  volcanic  glass. 

Oligoclase. — A  white,  sodium,  calcium  and  aluminum  silicate 
of  the  feldspar  group.  It  is  a  common  plagioclase  mineral  in 
granites. 

Olimne. — An  olive  green  silicate  of  magnesium  and  iron  crys- 
tallizing in  the  orthorhombric  system.  It  occurs  in  the  basic  and 
ultra-basic  igneous  rocks. 

Onyx. — The  true  onyx  is  a  cryptocrystalline  variety  of  quartz 
which  closely  resembles  an  agate.  The  onyx  marble  is  a  compact 
variety  of  limestone  which  is  noted  for  its  translucency,  and 
often  a  delicate  arrangement  of  colors  more  or  less  banded. 

Oolite. — A  granular  limestone  made  up  of  concentric  coats  of 


416  BUILDING    STONES   AND    CLAYS 

the  carbonate  of  calcium  deposited  around  minute  nuclei.  The 
grains  are  about  the  size  of  the  roe  of  a  fish. 

Opal. — A  noncrystalline  hydrous  variety  of  quartz. 

Ophicalcitc. — A  term  often  applied  to  the  coarsely  crystalline 
marbles  containing  serpentine. 

Ophhnagnesite. — A  rock  consisting  of  crystallized  magnesite 
and  disseminated  serpentine. 

Ophitic. — Consisting  of  interlacing  lath-shaped  crystals  of  feld- 
spars whose  interspaces  are  chiefly  filled  with  pyroxenes  of  later 
growth. 

Orbicular. — An  igneous  rock  having  its  component  mineral.} 
crystallized  or  segregated  in  spheroidal  forms.  The  term  is  ap- 
plied to  the  granite  of  Craftsbury,  Vermont,  and  to  the  cliorite 
of  San  Diego,  California. 

Ornamental  Brick. — A  term  often  applied  to  front  brick  which 
have  the  surface  ornamented  with  some  form  of  design. 

Orthoclase. — The  potassium  aluminum  silicate  of  the  feldspar 
group,  which  crystallizes  in  the  monoclinic  system.  It  is  a  neces- 
sary mineral  constituent  of  all  granites. 

Pale  Brick. — A  brick  which  is  underburned. 

Paring  Brick. — Vitrified  blocks  which  are  used  for  paving 
purposes. 

Pegmatite. — A  very  coarse  grained  phase  of  the  granite  rocks 
which  usually  occurs  in  dikes  or  lenses  intruded  in  granites  and 
metamorphic  rocks. 

Pcridotitc. — An  ultra-basic  igneous  rock  consisting  essentially 
of  olivine. 

Phcnocrysi. — One  of  the  prominent  crystals  in  a  rock  of 
porphyritic  texture. 

Phlogopite. — An  amber  mica  which  often  occurs  in  marbles 
and  serpentines. 

Pholeritc. — A  hydrous  silicate  of  aluminum  derived  from  the 
decomposition  of  orthoclase. 

Phonolitc. — A  felsitic  lava  which  rings  when  struck  with  a 
hammer. 

Phyllite. — A  fine  grained  metamorphic  rock  intermediate  be- 
tween a  slate  and  schist. 

Pipe  Clay. — A  term  applied  to  clays  used  for  the  manufacture 
of  se\ver  pipe. 

Pisolite. — A  concretionary  limestone  with  the  globules  about 
the  size  of  small  peas. 

Pitch. — The  inclination  of  the  axis  of  the  fold  of  a  rock, 

Plagioclasc. — A  collective  name  for  the  triclinic  feldspars  other 
than  microcline. 


GLOSSARY  417 

Plasticity. — The  property  of  certain  clays  to  form  a  plastic 
mass  when  mixed  with  water. 

Plutonic. — A  term  applied  to  the  granitoid  igneous  rocks  which 
have  cooled  a  considerable  distance  below  the  surface  of  the 
earth. 

Porphyritic. — A  term  applied  to  those  igneous  rocks  which 
contain  phenocrysts  of  some  mineral  in  a  finer  grained  ground 
mass. 

Pozzuolana. — A  volcanic  ash  used  as  an  hydraulic  cement. 

Pressed  Brick. — A  term  applied  to  smooth-faced  front  brick. 

Pseudotnorph. — A  mineral  that  has  assumed  the  crystal  form 
of  a  different  mineral  as  a  result  of  the  partial  or  entire  alter- 
ation or  replacement  of  the  original  mineral  through  chemical 
processes. 

Pudding  Stone. — Conglomerate  rock  containing  numerous 
rounded  pebbles. 

Pugging. — The  tempering  of  wet  clay. 

Pug  Mill. — A  machine  for  tempering  or  mixing  wet  clay. 

Pyrite. — A  common,  yellow,  metallic  sulphide  of  iron  which 
crystallizes  in  the  isometric  system. 

Pyroxene. — A  group  of  bisilicate  minerals  whose  cleavage 
angles  are  approximately  S?y2  degrees  and  92l/2  degrees.  Augite 
is  the  most  important  member  of  the  group. 

Pyro.i'enite. — A  basic  igneous  rock  consisting  essentially  of 
pyroxenes. 

Quarry. — An  opening  made  in  an  outcrop  of  rock  with  the 
purpose  of  obtaining  stone  for  commercial  purposes. 

Quarry  Water. — The  water  present  in  the  interstices  of  a 
stone  when  it  is  quarried. 

Quarts. — A  form  of  silica  occurring  in  hexagonal  crystals  or 
in  cryptocrystalline  massive  forms. 

Quartzite. — A  metamorphic  sandstone  whose  cement  is  silica. 

Quartz  Monzonite. — An  igneous  rock  of 'granitic  texture  con- 
taining quartz  with  the  plagioclase  minerals  equal  or  in  excess 
of  the  orthoclase. 

Quartz  Porphyry. — An  igneous  porphyrjtic  rock  of  the  same 
mineral  composition  as  granite  but  with  quartz  occuring  as  pheno- 
crysts. 

Repressed  Brick. — Brick  which  after  being  molded  are  run 
through  a  second  pressing  machine  to  improve  their  form. 

Residual  Clay. — One  formed  by  the  decay  of  rocks  in  situ. 

Rhyolite. — An  igneous  rock  with  the  same  mineral  composition 
as  granite  but  usually  with  a  porphyritic  texture. 

27 


418  BUILDING    STONES   AND    CLAYS 

Rhodonite. — A  silicate  of  manganese  which  is  susceptible  of  a 
high  polish  and  is  suitable  for  decorative  interior  work. 

Ribbon. — A  line  of  bedding  or  a  thin  bed  appearing  on  the 
cleavage  surface  in  slate.  Sometimes  it  is  of  a  different  color 
from  the  slate. 

Ridge  Tile. — A  roofing  tile  used  at  the  roof  ridge. 

Rift. — A  microscopic  cleavage  in  building  stones  which  greatly 
aids  in  the  process  of  quarrying. 

Ring  Pit. — A  circular  pit  in  which  clays  are  tempered  by  use 
of  a  large  revolving  wheel. 

Rock-Face  Brick. — Brick  with  their  surface  chiseled  so  as  to 
resemble  cut  stone. 

Roman  Tile. — Either  dry  pressed  or  stiff-mud  repressed  brick 
of  dimensions  12  by  4  by  1^  inches. 

Roofing  Tile. — A  term  applied  to  a  burned  clay  tile  used  for 
roofing  purposes. 

Run. — A  term  used  to  denote  the  course  of  the  rift. 

Saccharoidal. — A  texture  resembling  that  of  loaf  sugar. 

Salmon  Brick. — Underburned  brick  which  are  of  a  pale  salmon 
color. 

Salt  Glaze. — A  glaze  produced  on  sewer  pipe  and  stoneware 
by  adding  salt  to  the  kiln  fires  during  the  process  of  burning. 

Sand. — Finely  comminuted  fragments  and  water  worn  particles 
of  rocks. 

Sandstone. — A  sedimentary  rock  consisting  of  grains  of  sand 
held  together  by  some  cementing  material. 

Sap. — A  term  often  used  by  quarry  men  to  denote  the  more  or 
less  weathered  portion  of  any  rock  mass. 

Saprolite. — Thoroughly  decomposed  but  untransported  rock. 

Schist. — A  metamorphic  rock  which  has  a  parallel  or  foliated 
structure  secondarily  developed  by  shearing.  Schists  frequently 
consist  of  grains  of  quartz  and  scales  of  mica  arranged  in  more 
or  less  parallel  layers.  Feldspathic  particles  may  be  present. 

Schistose. — Having  the  structure  of  a  schist. 

Scove  Kiln. — A  temporary  kiln  often  used  in  burning  common 
brick. 

Sculping. — Fracturing  the  slate  along  the  grain  ;  that  is,  across 
the  cleavage  in  the  direction  of  the  dip. 

Seam. — A  term  often  used  for  any  fracture  occurring  in  a  rock 
mass. 

Sedimentary  Rocks. — Those  which  have  been  deposited  after 
being  more  or  less  sorted  by  running  water. 

Selenite. — A  variety  of  gypsum  which  is  transparent  and 
usually  occurs  in  plates. 


GLOSSARY  419 

Seuii-Dry-Press  Process. — Closely  related  to  the  dry-press 
process  but  the  clay  is  more  moist. 

S  eric  it  e. — An  altered  muscovite  occurring  in  scales  or  fibrous 
forms. 

Serpentine. — A  metamorphic  rock  consisting  essentially  of  the 
mineral,  serpentine.  The  coarser  massive  varieties  are  used  as 
structural  stone.  The  more  highly  colored  varieties  for  interior 
decoration. 

Settle. — The  amount  of  fire  shrinkage  which  takes  place  in  a 
kiln  of  brick  during  the  process  of  burning. 

Sewer  Brick. — Low  absorption  brick  used  as  sewer  linings. 

Shale. — A  fine  grained,  laminated,  argillaceous  rock,  usually 
with  friable  structure. 

Shaly. — A  term  used  to  describe  a  thin  bedded  rock  which 
breaks  up  like  shale. 

Sheeted  Structure. — A  term  applied  to  those  granite  quarries 
which  have  well  defined  horizontal  joints  and  but  few  vertical 
joints. 

Shingle  Tile. — A  flat  form  of  roofing  tile. 

Shrinkage. — The  decrease  in  volume  which  clays  undergo  dur- 
ing the  processes  of  drying  and  burning. 

Siderite. — A  carbonate  of  iron  which  crystallizes  in  the  hexa- 
gonal system  in  rhombohedrons  with  curved  faces.  When  present 
in  a  building  stone  it  is  an  objectionable  accessory  constituent. 

Siding  Tile. — Any  roofing  tile  used  in  upright  work. 

Siliceous. — Containing  an  appreciable  amount  of  silica  as  an 
impurity. 

Silt. — A  muddy  deposit  in  bays  and  harbors.  A  soil  whose 
grains  vary  from  .05  to  .005  mm.  in  size. 

Slate. — A  metamorphosed  clay  or  shale.  It  usually  has  a  well 
developed  cleavage  which  is  at  right  angles  to  the  pressure  which 
aided  in  the  metamorphism. 

Slickensides. — Polished  and  grooved  surfaces  produced  by  one 
mass  of  rock  sliding  over  another  as  along  a  fault  plane. 

Slip. — Joints  crossing  the  cleavage  but  of  no  great  continuity. 

Slip  Clay. — Any  easily  fusible  clay. 

Slip  Cleavage. — Microscopic  folding  and  fracture  which  is  ac- 
companied with  slippage. 

Slip  Glaze. — One  produced  by  the  use  of  slip  clay. 

Slop  Brick. — A  term  often  applied  to  soft-mud  brick. 

Slurry. — A  term  applied  to  the  semi-wet  mixture  when  ground 
and  ready  for  burning  in  rotary  kiln. 

Soak  Pit. — A  pit  in  which  clay  is  soaked  before  molding. 


420  BUILDING    STONES   AND    CLAYS 

Soft-Mud  Process. — A  method  of  molding  brick  by  forcing 
them  into  wooden  molds. 

Spanish  Tile. — A  term  applied  to  roofing  tile  with  an  S-shaped 
cross  section. 

Specific  Gravity. — The  weight  of  a  mineral  or  rock  when  com- 
pared with  the  weight  of  an  equal  volume  of  water. 

Split. — A  slaty  cleavage. 

Stalactite. — An  icicle-like  deposit  of  the  carbonate  of  calcium, 
formed  on  the  roof  of  caves  by  the  evaporation  of  the  solvent. 

Stalagmite. — A  deposite  of  the  carbonate  of  calcium  formed  on 
the  floor  of  caves  by  the  evaporation  of  the  solvent. 

Steatite. — A  massive  variety  of  talc. 

Stiff -Mud  Process. — A  method  of  molding  brick  by  forcing 
plastic  clay  through  a  die. 

Stock. — A  large  columnar  mass  of  igneous  rock  with  appoxi- 
mately  equal  length  and  breadth. 

Stock  Brick. — The  carefully  selected  bricks  of  a  kiln. 

Stratification. — Bedding,  in  distinction  from  cleavage. 

Stratum. — A  layer  or  bed  of  rock. 

Stretcher. — A  stone  or  brick  laid  with  its  longer  axis  parallel 
to  the  face  of  the  wall. 

Strike. — A  direction  at  right  angles  to  the  inclination  of  a 
plane  of  bedding,  cleavage,  or  jointing;  the  trend  of  an  outcrop. 

Strike  Joint. — A  joint  parallel  to  the  strike  of  the  cleavage. 

Stripping. — The  process  of  removing  worthless  material  from 
'<?.  quarry. 

Sulphur. — A  term  often  used  by  quarrymen  to  denote  iron 
pyrite.  Also  the  element  sulphur. 

Syenite. — An  intermediate  igneous  rock  whose  mineral  com- 
position is  essentially  orthoclase  and  hornblende. 

Syenite  Gneiss. — A  sheared  syenite.  A  syenite  with  its  ferro- 
magnesian  minerals  arranged  in  parallel  layers. 

Syenite  Porphyry. — A  rock  with  porphyritic  texture  but  of  the 
same  mineral  composition  as  a  syenite. 

Syncline. — The  trough  part  of  a  fold  of  rock. 

Synclinorium. — A  mountain  mass  with  its  general  internal 
structure  trough-shaped. 

Talc. — A  hydrous  silicate  of  magnesium  which  is  number  1  in 
the  scale  of  hardness. 

Talc  Schist. — A  schistose  rock  consisting  essentially  of  talc  and 
quartz. 

Talus. — The  collection  of  earth  and  broken  rock  at  the  foot  of 
a  cliff  or  steep  slope.  This  material  when  angular  is  sometimes 
cemented  together  as  a  talus  breccia. 


GLOSSARY  421 

,  Tapestry  Brick. — Brick  made  by  the  stiff-mud  process  and 
having  all  surfaces  roughened  by  wire  cutting. 

Tempering. — The  process  of  properly  mixing  clays  before 
molding. 

Terra  Cotta. — A  kind  of  hard  pottery  used  for  statues  and 
architectural  decorations.  Sometimes  applied  to  a  certain  type  of 
blocks  used  in  constructional  work. 

Terra-Cotta  Clay. — Any  clay  that  may  be  used  in  the  manu- 
facture of  terra  cotta. 

Terra-Cotta  Lumber. — A  term  applied  to  fireproofing  shapes 
of  clay  ware  which  are  soft  and  porous. 

Thick  Joint. — Two  or  more  parallel  joints  between  rocks  which 
have  been  broken  up  or  decomposed. 

Till. — A  mixture  of  clay  and  pebbles  which  have  been  left  by  a 
glacier. 

Toe  Nail. — Curved  joints  intersecting  a  sheet  structure. 

Top. — The  weathered  portion  or  shattered  upper  portion  of  any 
rock  mass. 

Trachyte. — An  intermediate  eruptive  rock  consisting  essentially 
of  orthoclase  and  one  or  more  ferromagnesian  minerals. 

Trap. — A  field  name  for  any  dark  fine  grained  igneous  rock. 

Travertine. — A  calcareous  rock  deposited  from  solution.  The 
compact,  translucent  variety  is  known  as  onyx  marble. 

Tremolite. — A  white  variety  of  amphibole  which  sometimes 
occurs  as  an  objectionable  constituent  in  marbles. 

Unakite. — A  peculiar  granite  whose  mineral  composition  is 
orthoclase,  quartz  and  epidote. 

Unctuous. — Having  a  greasy  or  soapy  feel. 

Updraft  Kiln. — A  kiln  in  which  the  heat  enters  from  the  bottom 
and  passes  upward  through  the  ware  during  the  process  of 
burning. 

Valley  Tile. — Roofing  tile  made  to  fit  the  valley  of  a  roof. 

Vein. — A  more  or  less  regular  mineral  mass  consisting  of 
quartz,  with  or  without  calcite.  Its  presence  is  objectionable  in 
a  slate  quarry.  Also  the  filling  of  a  fissure. 

Verd  Antique. — A  metamorphic  rock  consisting  essentially  of 
serpentine  traversed  by  veinlets  of  talc,  calcite  or  dolomite.  It 
is  susceptible  of  a  polish,  and  is  a  marble  only  in  a  commercial 
sense. 

Vesicular. — A  term  often  applied  to  lavas  containing  air  or 
gas  cavities. 

Volcanic. — A  term  applied  to  surface  flows  of  igneous  rocks  to 
distinguish  them  from  rocks  which  have  cooled  from  molten  solu- 
tion beneath  the  surface. 


422  BUILDING  STONES  AND  CLAYS 

Volcanic  Ash. — A  term  applied  to  the  fine  grained  volcanic 
ejectamenta.  When  consolidated  it  is  sometimes  used  for  build- 
ing purposes. 

Volcanic  Tuff. — A  consolidated  volcanic  ash. 

Wall  White. — A  white  scum  often  seen  on  brick  after  setting 
in  a  wall. 

Waves. — A  term  often  applied  to  annelid  trails. 

Weathering. — A  term  applied  to  the  changes  that  occur  in 
rocks  due  to  physical  and  chemical  agencies. 

Whitewash. — A  term  applied  to  the  white  scum  of  soluble 
sulphates  which  often  appears  on  the  surface  of  brick  and  other 
clay  products  either  during  or  after  their  manufacture. 

Wind  Rock. — A  term  applied  to  slate  unfit  for  commercial 
purposes. 

Xenolith. — A  mass  of  rock  included  in  any  irruptive  in  its  mi- 
gration towards  the  surface. 

Zeolites. — A  name  for  a  group  of  closely  related  minerals 
which  are  essentially  hydrous  silicates  of  aluminum,  with  potas- 
sium, sodium,  calcium  and  more  rarely  barium.  They  are  of 
secondary  origin. 

Zircon. — A  silicate  of  zirconium,  which  crystallizes  in  the 
tetragonal  system  and  often  occurs  as  an  accessory  mineral  in 
granite. 

Zonation. — The  arrangement  of  igneous  rocks  in  more  or  less 
concentric  belts  or  zones  due  to  differentiation  during  the  process 
of  cooling.  It  is  the  most  pronounced  near  the  walls  where  cool- 
ing began. 


INDEX 


Aberdeen,  Scotland,  98 

Acervularia  davidsoni,  161 

Actinolite,  7 

Aegirite,   57 

Alberene,  Virginia,  317 

Albite,   4 

Algae,  138,  139 

Alkalies,  331 

Allanite,    67,   94 

Alumina,  329 

Amphibole,   6 

Andesine,  4 

Andesite,  136 

Angers,  France,  293 

Ankerite,  13 

Anorthite,  4 

Antigorite,  193 

Apatite,  38,  94 

Aplite,   120 

Aragonite,  10,  134,  154 

Artificial  brick  colors,  350 

Artificial  stone,  394 

artificial  terra  cotta,  402 

Beton-Coignet,   394 

cut  cast  stone,  397 

Frear  stone,  395 
hardness  of,  394 

McMurtrie  stone,  395 

marble,  396 

Portland  stone,  394 

quality  of,  394 

Ransome  stone,  395 

references,  402 

Sorel  stone,  394 

strength  of,  394 
Ashley,  G.  H.,  138 
Aspdin,  Joseph,  383 


Aspen,  Colorado,  152 
Atlantic  terra  cotta,  402 
Aubury,  L.  E.,  305,  315 
Augite,  8 

Augite  granite,  39 
Augite  syenite,  60 
Augusta,  Maine,  52 

B 

Baker,   I.   O.,   357 

Baltimore,  Maryland,  56 

Bancroft  marble,  210 

Bardiglio  marble,  200 

Barney  Marble  Company,  187, 193 

Barre,  Vermont,  84,  118 

Basalt,  127 

Bay  of  Fundy  granite,  96 

Beaver  Creek,  Colorado,  45 

Becker,  A.,  140 

Beebe  Plains,  Vermont,  83 

Berkey,  C.  P.,  232      , 

Bethel,  Vermont,  3,  81,  90,  118 

Bickford,  G.  H.,  88 

Biotite,  5 

Biotite  granite,  39 

Black  granite,  51,  53,  55 

Black  marble,  Italy,  204 

Blatchley,  W.  S.,  138 

Bleininger,  A.   V.,   349 

Bloomington,  Illinois,  360 

Boeke,  H.  E.,  140 

Bougard   marble,   199 

Boulder  quarry,  86 

Brachernagh  marble,  200 

Brandon,  Vermont,  172 

Branford,  Connecticut,  45 

Branner,  J.  C.,  235 

Breccia  marble,  204 

Bristol,  Connecticut,  47 


423 


424 


INDEX 


Brocatelle  marble,  199,  202 
Broadway,  New  York  City,  373 
Buckley,  E.  R.,  273 
Buffalo  Hill,  Vermont,   76 
Building  brick,  345,  354 

Classification,    method    of 

molding,  351 
machine   made,   352 
pressed  brick,  352 
sanded  brick,  352 
stock  brick,  352 
stiff  mud  brick,  352 
Classification,  position  in  kiln, 

352 

arch  brick,  353 
body  brick,  353 
cherry  brick,  353 
clinker   brick,353 
hard  brick,  353 
salmon  brick,  353 
soft  brick,  353 
Classification  by  use,  353 
compass  brick,  353 
face  brick,  353 
feathered  edge,  353 
paving  brick,  354 
vitrified    brick,    354 
Burning,  347 
Circular  kilns,  348 
Common  brick,  345 
Dehydration,  348 
Down  draft  kiln,  348 
Dry  clay  machine,  347 
Enameled  brick,  345 
Fire   brick,  345 
Molding,   347 
Building  brick,  345 
oxidation,  348 
pressed,  345 
soft  mud  machines,  347 
stiff  mud  machines,  347 
vitrification,   34 
water  smoking,  348 
Tests  for,  354 
Absorptive  power,  355 
Compressive  strength,  356 
Form,   354 
Production,  1914,  356 


Production,   1915,    357 
References,  360 
Texture,  355 
Building  stone,  217 
ashlar  blocks,  217 
cobble  houses,  217 
diagonal  jointed,  218 
grooved  face,  218 
hammered  face,  218 
hammered  finish,  219 
polished  face,  219 
sawed  face,  219 
smooth  face,  219 
square  drove,  218 
toothed  chiseled,  218 
uniform  jointed,  217 
Building  stones,   1 

chemical   properties,   21 
color  of,  15 
compression,  29 
definition  of,  1 
life   of,   33 
minerals  of,  1 
rift  and  grain,  27 
structures    of,   22 
transverse  strength,  29 
weathering,  29 

bacteria,  32 

chemical,  29 

induration,  33 

friction,   33 

frost,  33 

physical   agencies,    32 

vegetation,   32 

Building  stone,  methods  of  test- 
ing, 35 

abrasive   test,   35 
absorption  test,  36 
color  test,  35 
compression  test,  37 
contraction  test,  36 
corrosion  test,  35 
elasticity  test,  36 
expansion  test,  36 
fire  resisting  test,  36 
freezing  test,  36 
shearing  test,  37 
specific  gravity  test,  37 


INDEX 


425 


Building  stone,  physical  proper- 
ties, 15 
density,  18 
hardness,  17 
selection  of,  34 
specific  gravity,  18 
state  of  aggregation,  21 
texture  of,   20 


Cabot,   Vermont,   86 
Caen,  Normandy,   199 
Calais,  Vermont,  87 
Calcareous  clays,  331 
Calcite,  10 

Caledonia  County,  Vermont,  75 
Calera,  Alabama,  144 
California  onyx,  154 
Canaan,  Connecticut,  156 
Carbonates,   10 
Carpenter,  J.  F.  W.,  28 
Carrara,  Italy,  135,  141 
Catskill,  New  York,  335 
Cayeux,   L.,   233 
Cement,  383 

activity  of,  391 

chemical  composition  of,  391 

clinker,  388 

color  of,  390 

contraction  of,  391 

disintegration  of,  391 

dry  process,  388 

expansion  of,  391 

fineness  of,  391 

grinding  of,  388 

history  of,  383 

hydraulic,  383 

hydraulic  lime,  385 

lime  mortar,  385 

natural  cement,  383,  385,  390, 
391 

Portland  cement,  383,  386,  390 

pozzuolana,  389 

properties  of,  390 

quarrying  of  rock,  386 

quicklime,  384 

Roman,  383 

Rosendale,  385 


rotary  kilns,  388 
semi-wet  process,  388 
slag,  390 

soundness    of,   391 
specific  gravity  of,  390 
white  Portland,  389 
Chamberlin,  T.  C.,  95,  326 
Chara,  138 

Charlestown,  West  Virginia,  360 
Chatham,  Canada,  135 
Chelsea,   Vermont,    78 
Childersberg,  Alabama,  145 
Chlorite,  9 
Chrusthov,  K  ,  80 
Chrysolite   group,   8 
Chrysotile,   193 
Clarke,  F.  W.,  139,  143,  235 
Clarke,  J.  M.,  139 
Glaus,  C.,  235 
Clowes,' F.  ,234 
Clays,  323 

adobe  clays,  326 
aerial  tramway,  339 
air  shrinkage,  328 
chemical  components,  329 
alkalies,  331 
alumina,    321 
analysis,  333 
iron,  330 
kaolinite,  32  9 
lime,  331 
magnesia,   331 
manganese  oxide,  332 
organic  matter,  333 
silica,  329 
sulpruric  acid,  332 
titanium  dioxide,  332 
water,  332 

chemical  composition,  323 
circular  tubs,  340 
color  of,   327 
crushing,  340 
cyclonic  separation,  342 
definition  of,  323 
drifting,  339 
employment  of,  342 
eolian,  325,  325 
fire  shrinkage,  328 


420 


INDEX 


fusibility  of,  327 

geological  horizon,  326 

glacial  clays,  324,  325 

haulage,    329 

lake  clays,   324 

loess  clays,  325 

log  washing,  340 

marine  clays,  324 

mineral  composition,  323 

mining,  336 

mining  and  washing,  336 

open  pit,  326 

origin,  324 

origin  of  eolian  clays,  326 

physical  properties,  326 

plasticity,   326 

preparation   of,   340 

presses,  341 

quarrying,  336 

references,  344 

residual  clays,  324,  325 

revolving  screens,  341 

screening,    340 

sedimentary  clays,  325 

settling  tank,  341 

shaft,  339 

size  of  grains,  323 

slaking,  327 

stationary  screens,  341 

steam   haulage,  339 

steam  shovel,  336 

stream  clays,  324 

tensile  strength,  327 

test  for  fineness,  323 

transported  clays,  324 

underground  mining,  338 

undermining,  338 

uses,  342 

decorative,  342 
domestic,  342 
engineering  works,  343 
hygienic,  342 
minor  uses,  343 
refractory  wares,  343 
structural  uses,  342 

value  of,  342 

washing,  340 

washing  trough,   341 


wheel  scraper,  336 

yield,  342 

Cockeysville,   Maryland,  162 
Cohn,  F,  138 
Conchite,  134 
Concord,  New  Hampshire,  62,  66r 

118 
Concrete,  392 

advantages  of,  392 

gravel  vs.  broken  stone,  393 

Portland  vs.  natural  cement,. 
393 

theory  of,   392 

wet  vs.  dry  concrete,  393 
Coquina,  136,  158 
Craftsbury,  Vermont,   6,  79 
Crosby,  W  O.,  25,  66,  118,  306 
Cumberland   County,  Maine,  49 
Cut  cast  stone,  402 

D 

Dale,  T.  N.,  27,  48,  56,  57,  66,  72r 
80,  81,  88,  93,  189,  270r 
272,  275,  277,  281,  291 
Ball,   W.   H.,    139 
Daly,  R    A.,  93 
Dana,  J.  D.,  32,  237 
Davis,  C.  A.,  138 
Day,  W.  C.,  118,  262 
Derby,  Vermont,  82 
Diabase,  127 
Diorite,  128 
Dodge,  J    A.,  35,  36 
Dolomite,  11 

definition  of,  134,  135 

origin  of,  137 
Dolomite   (rock),  142 

color  of,   143 

tests  for,  143 
Dorset,  Vermont,  170 
Dorset    Mountain    Marble    Com- 
pany, 173 
Doss,  B.,   234 
Dummerston,  Vermont,  90 

E 

Eakins,  L.  G.,  268 

East  St.  Cloud,  Minnesota,  61 


INDEX 


427 


Eckel,  E.  C.,  272,  273,  288,  259, 

335 

Emerson,   B    K.,   56 
Enfield,  New  Hampshire,  9 
Enstatite,  7,  314 
Epidote  granite,  71 
Epidote  group,  8 
Essex  County,  Vermont,  78 
Everglades,  Florida,  138 


Fayetteville,  New  York,  383 
Feldspars,  3 
Finlay,  G.  I.,  28 
Fire  clays,  323,  326 
Flagstaff,  Arizona,  235 
Fletcher  quarries,  88 
Fletcher,  Robert,  386 
Flexible  sandstone,  229 
Fluorite,  198 
Flynt,  W.  N.,  119 
Ford,  W.  E.,  233 
Forest  marble,  198 
Formosa  marble,  199 
Fort  Marion,  Florida,  158 
Fountain  sandstone,  236 
Fox  Island,  Maine,  52 
Francestown,    New    Hampshire, 

315 

Franklin  County,  Maine,  50 
Fredericksburg,  Virginia,  94 
Freedly,  J.  K.  &  Sons,  171 
Freeport,  Maine,  49 
French  chalk,  320 
French  gray  marble,  190 
French  red  marble,  198 
Frosterus,  B.,  81 
Fryeburg,  Maine,   53 
Fuller's  earth,  331 

G 

Gabbro,  128 
Garnet,  14 
Geiger,  W.  F.,  254 
Georgetown,  Colorado,  44 
Gilbert,  G.  K.,  138 
Glacial  boulders,  382 
Glauconite,  330 


Glens  Falls,   New  York,  15,  144 
Glossary,  406 
Gneiss,  38,  129,  375 
Gneissoid   granite,   380 
Goodsell  &  Fleury,  190 
Gouverneur,  New  York,  167 
Granites,  38 

Granites,   American,   42 
California,  42 
Colorado,  42 
Connecticut,  45 
Delaware,   47 
Georgia,  47 
Maryland,  55 
Massachusetts,  56 
Milford,  56 
Quincy,  57 
Rockport,  59 
Minnesota,  60 

East  St.  Cloud,  61 
Missouri,  61 
Montana,  61 
New  Hampshire,  61 
Concord,  62 
Conway,  66 
Milford,  67 
Sunapee,  68 
New  York,  69 

Grindstone  Island,  69 
Keeseville,  69 
Picton  Island,  69 
North   Carolina,    70 
Oklahoma,  71 
Pennsylvania,  71 
Rhode  Island,  71 
South  Carolina,  73 
Tennessee,  73 
Texas,  73 
Utah,  74 
Vermont,  74 
Barre,  84 
Bethel,  90 
Cabot,  86 
Calais,  87 
Chelsea,  70 
Craftsbury,  79 
Derby,  82 
Dummerston,  90 


428 


INDEX 


Groton,  75 

Hardwick,  75 

Irasburg,   84 

Kirby,  76 

Newark,  77 

Randolph,  78 

Ryegate,  77 

Topsham,  78 

Williamstown,  79 

Windsor,  91 

Woodbury,  87 
Virginia,  94 
Wisconsin,  95 
Wyoming,  96 

Granites,  Foreign,  96 
British  Columbia,  96 
Egypt,  98 
England,   97 
Ireland,  98 
New  Brunswick,  96 
Nova  Scotia,  96 
Ontario,  96 
Quebec,   96 
Scotland,  98 
Sweden,  100 

Granites,  Properties  of,  38 
chemical  analyses,  117 
compression  tests,  116 
definition  of,  38 
economic   classification,   39 
mode  of  occurrence,  39 
name  of,  39 
origin   of,    38 
polishing,    114 
quarrying,    112 
references,  132 
table  showing  specific  gravity 

etc.,  131 
uses,  100 

Graniteville,  Quebec,  83 
Graniteville,  Vermont,  84 
Greenville,   Georgia,   334 
Greenwich,  Connecticut,  47 
Griswold,  L.   S.,   236 
Groton,  Vermont,   75 
Gypsum,    11,   396 


H 

Hager,  A.  D.,  80 

Hall,  James,   13 

Hall,  Sir  James,  140 

Hallowell,  Maine,  52 

Hancock  County,  Maine,   50 

Hardwick,   Vermont,   75 

Hardwood  Island,  Maine,  55 

Hawes,   G.,   80 

Hayes,  C.  W.,  234,  274 

Headon,  W.  P.,  29 

Hematite,    13,   330 

Hill,  R.  T.,  342 

Hillebrand,  W.  H.,  288,  298,  299, 

300 

Hirschwald,  J.,   30 
Hitchcock,  C.  H.,  78,  80,  93,  170, 

274,   315 

Hopkins,  T.  C.,  154,  238,  250 
Hornblende,  7 

Hornblende    granite,    39,    59,    79 
Hot  Springs,  Arkansas,  334 
Howe,    J.    A.,    34,    139,    142,    196, 

197,  254,  255 

Hudson  River  bluestone,  232 
Hume,   W.   F.,   326 
Hungerford  marble,  211 
Hunt,  T.  S.,  142,  222 
Hutchins,  W.   M.,   268 
Hydraulic  cement,  383 
Hydraulic  lime,   385 
Hygroscopic  moisture,  332,  333 
Hypersthene,  7 


Imperial  blue  granite,  88 
Important  stone  structures,  404, 

405 

Inlaid  Slate  Company,  296 
Iowa  City,  Iowa,  160 
Irasburg,  Vermont,   84 


Jackson,  J.  J.,  42 
Johannis,  A.,  140 
Joint  planes,  22 
Jonesport,  Maine,  55 
Julien,  A.,  13,  34 


INDHX 


429 


K 

Kaolin,  324 

Kaolinite,  323,  324,  329,  333 

Keeseville,  New  York,  7,  69,129 

Keith,  C.  L.,  281 

Kemp,  J.  F.,  117,  141 

Kendall,  F.  P.,  139 

Kennebec  County,  Maine,  52 

Kettle  River  sandstone,  377 

Key  West,  Florida,  158 

Kingston,  Ontario,  96 

Kinnicut,  L.  P.,  119 

Kirby,  Vermont,  76 

Kitchell,  W.,  138 

Knox  County,  Maine,  52,  17 


Labradorite,  4 
Lake  clays,  324 
Lake  district,  England,  269 
Landscape  marble,  198 
Languedoc  marble,  199 
Lawson,  Colorado,  44 
Le  Chatelier,  H.,  140 
Lepidomelane,  6 
Leuce,  G.,  142 
Levante  marble,  200 
Lewis   &  Chandler,   389 
Lewis,    J.    V.,    244 
Lexlip   marble,  200 
Lime  mortar,   384,  385 
Limerick  marble,  200 
Limestone,   134 
age  of,  144 
alteration  of,  141 
color  of,   143 
coquina,  136 
coralline,   136,   139 
crinoidal,  137,  140 
definition  of,  134 
distribution  of,   144 
dolomitic,  134,  135 
fossiliferous,    136 
Gasport,  168 
hardness  of,  144 
hydraulic,  135 
impurities  in,  135 
lithographic,  135 


Lockport,   168 

Manlius,   167 

marbleization  of,  140,  141 

Niagara,   168 

Onondaga,    167 

oolitic,  135 

origin  of,  137 

Rochester,  168 

specific  gravity  of,  144 

stalactite,   136 

stalagmite,   136 

texture  of,   135 

travertine,  136 

Trenton,  168 

varieties   of,    135 
Limonite,   330 
Lincoln  County,  Maine,  53 
Liparite,    126 

Little   Cottonwood  Canon,  Colo- 
rado, 74 

Loess  clays,  325 
Logan,  W.  E.,  188 
Lowville,   New  York,   167 
Luray  Caverns,  Virginia,  137 
Lyell,   Sir  Charles,   137 

M 

Machie,  M.,  235 
Madoc  marble,  211 
Magnesite,   143 
Magnetite,  11,  14,  193 
Maine  Red  Granite  Company,  54 
Mansfield,  England,  142 
Mansfield  sandstone,  239 
Marble,   134 

age  of,  144 

analyses  of,  222 

Carrara,  Italy,  134 

color  of,   143 

compression  tests,  221 

definition   of,   134 

distribution  of,   144 

dolomite,   135 

dressing,   212 

hardness   of,   144 

manufacture  of,  212 

onyx,  136 

origin  of,  137 


-130 


INDEX 


quarry,  221 

references,   226 

saccharoidal,   135 

specific  gravity  of,  144 

stalactitic,  137 

stalagmitic,  137 

table  showing  specific  gravity 

etc.,  225 
uses,  221 

Marbles,  American,  144 
Alabama,  144 

age  of,  148 

bedding,  149 

jointing,  149 

quarries,  146 

quarrying,  150 

structural  relations,  146 

texture  of,  145 

thickness,  152 

topography,  148 

uses  of,  146 
Arizona,  152 
Arkansas,  152 
California,  152 
Colorado,  155 
Connecticut,  156 
Delaware,  157 
Florida,   158 
Georgia.   158 

Creole,  159 

Etowah,   159 

silver  gray  Cherokee,  159 

southern,  159 
Idaho,   159 
Iowa,  159 
Illinois,   161 
Indiana,  162 
Kentucky,   162 
Maryland,   162 
Massachusetts,  162 
Minnesota,   163 
Missouri,  163 
Montana,  164 
Nevada,  164 
New  Jersey,  164 
New   York,  165 

Champlain  belt,  165 

Central  belt,  167 


Hudson  River  belt,  165 
St.  Lawrence  Valley  belt, 

167 

North  Carolina,  168 
Ohio,   168 
Pennsylvania,  168 
Tennessee,   169 
Vermont,    170 

distribution,  170 

Isle  La  Motte  belt,  190 

age  of,  191 
Plymouth  belt,  189 
age  of  189 
composition  of,  190 
Roxbury  belt,  193 

composition   of,   193 
Rutland   belt,   171 
age   of,   171 
Brandon,    177 
covered  quarry,  175 
Dorset  Mountain,  171 
mouring  vein  quarry,  176 
Pittsford,  176 
Proctor,    176 
West    Rutland,    173 
varieties,  177 
Albertson,    177 
American  pavanazzo,  178 
American  yellow  pavan- 
azzo,   178 
avenatto,  178 
best  light  cloud  Rutland, 

178 

Brandon  Italian,   178 
broccadillo,  178 
cipolina,    178 
dark  Florence,  178 
dark  vein  true  blue,  178 
Dorset   A,   178 
Dorset  B,  180 
Dorset   green   bed,    178 
dove   blue   Rutland,   180 
Esperanza,    180 
Fisk  black,  180 
florentine  blue,  180 
jasper,   182 

light     Rutland     Italian, 
182 


INDEX 


431 


listavena,  182 

livido,  182 

lyonnaise,    182 

marine  venoso,  183 

moss   vein,   183 

olive,  183 

oriental,  183 

pink   listavena,   183 

Riverside,  183 

royal  red,   184 

rubio,  184 

Rutland  building,  184 

special  Rutland   Italian, 
184 

standard  green,  184 

Swanton  dove,  184 

true  blue 

verd  antique,  185 

verdoso,  185 

vert  de  mere,  185 

Westland  cream,  185 
Washington  belt,  191 

age  of,  193 

origin  of,  192 

rhodonite,   193 

Waits  River,  192 

Washington,    191 
Winooski  belt,  185 

age  of,  189 

color  of,   186 

composition  of,  186 

origin  of,  186 
Virginia,   184 

Blacksburg,  195 
Buchanan,  195 
Craigsville,  195 
Giles  County,  195 
Goose  Creek,  195 
Lexington,  195 
Luray,  195 
New  Market,  194,  195 
Tye   River,  195 
Woodstock,  194 
.Marbles,  Foreign,  196 
Africa,  196 
Austria,  196 
Belgium,  196 
Bermuda,  197 


British  Columbia,  197 

England,  197 

France,  198 

Greece,  210 

Ireland,  200 

Italy,   200 

Mexico,   210 

Nova  Scotia,  210 

Quebec,  210 
Marbleization,  140 
Marcasite,    13 

Massachusetts     Highway     Com- 
mission, 380 
McCullock,  G.,  298 
McGee,  W.  J.,  326 
McKenna,  C.  F.,  118 
Medina  sandstone,  377 
Mennell,  F.  P.,  260 
Merrill,  G.  P.,  37,  42,  62,  138, 168, 
175,  196,  234,  235,  238, 
245,  296,  306 
Merriman,  M.,  297 
Micas,  5 
Microcline,  4 
Middleton,  J.,  343 
Milford,  Connecticut,  156 
Milford,    Massachusetts,    56,    119 
Milford,  New  Hampshire,  67 
Mineral,  2 

accessory,  2 

definition  of,   2 

essential,  2 

original,  2 

secondary,  2 
Minerals  of  building  stone,  1 

classification  of,  2 

essential,  2 

non-essential,  2 

number  of,  2 
Monzonite,  120 
Morrisville,  Alabama,  334 
Mosses,  138 
Mount  Ascutney,  Vermont,  8,  15, 

91 

Mount  Desert,  Maine,  50 
Murchison,  R.  I.,  257 
Muscovite,  5 
Muscovite  granite,  39 


432 


INDEX 


N 

Nephelite,  8 

Newark  pink  granite,  77 
Newark,  Vermont,  77 
Newberry,  J.  F.,  164 
Newfane,  Vermont,  81 
Nichols  Ledge  granite,  89 
Nontronite,  323 
Nordmarkite,   15,   93 
Norite,   69,,   129 
North  Conway,  New  Hampshire, 

66 

Northfield,  Vermont,  81,  284 
North  Jay,  Maine,  50,  17 
North   Troy,  Vermont,   307 
Novaculite,  236 

O 

Oligoclase,  4 

Olivine,   8 

Olmstead,   D.,   223 

Onondaga     Litholite     Company, 

•401 

Ophicalcite,  303 
Ophimagnesite,    303 
Orange  County,  Vermont,   78 
Orbicular  granite,  79,  81 
Orleans  County,  Vermont,  79 
Orthoclase,  4,   333 
Orton,  E.,  259,  349 
Owen,    D.    D.,    235 
Oxalic  acid,   116 
Oxford  County,  Maine,  53 


Paragneiss,  130 
Parker,  Joseph,  383 
Paving   brick,   361 

abrasion  of,  370 

absorption,   369 

burning,  364 

clays   for,   361 

crushing  strength,  368 

definition   of,   361 

down  draft  kilns,   364 

drying,  364 

form  of,  365 

history  of,  361 


impact,    370 

impure  fire  clays,  362 

manufacture  of,  362 

merits  of,  370 

molding,    363 

price  of,  371 

repressing,   363 

requisites,  366 

shales,    361 

size  of,  365 

specific  gravity  of,  367 

surface  clays,   361 

testing,  367 

transverse  strength,  368 
Paving  materials,  361 
Peale,  A.  C.,  243 
Pegmatite,   325 
Penfield,  S.  L.,  233 
Penobscot  County,  Maine,  53 
Penrhyn,  California,  42 
Peridotite,   315 
Perkins,  G.  H.,  175,  188 
Perry,  J.  H.,  56 
Peterhead,  Scotland,  15,  98 
Petersburg,    Virginia,   94 
Pfaff,  F.  W.,  143 
Philadelphia,   Pennsylvania,    71 
Phillips,  W.  B.,  253 
Phlogopite,   5 
Pholerite,  334 
Phonolite,  126 

Pittsford,  Vermont,  172,  176 
Placerville,  California,  269 
Plastic  clays,  326 
Plattsburg,  New  York,  165 
Point  of  Rocks,  Maryland,  162 
Porphyritic,  41,  98 
Porphyry,  120 

Port  Henry,  New  York,  165 
Portland  sandstone,  239 
Portor  marble,   202 
Potsdam  sandstone,  244,  376 
Pownal,  Maine,  49 
Pratt,  J.  H.,  315 
Pratts  Ferry,  Alabama,  144 
Prouty,  W.  F.,  144 
Providence,  Rhode  Island,  159 
Pyrite,  12,  330 


INDEX 


433 


Pyrophyllite,  315 
Pyroxene  group,  7 
Pyroxenite,  315 
Putty  powder,  114,  116 

Q 

Quartz,  3 
Quartzite,   232 
Quartz  monzonite,  73,  76,  82,  90, 

96 

Quicklime,  384 
Quincy,     Massachusetts,     7,     57, 

119 

R 

Randall,  T.  A.  &  Co.,  369 
Randolph,   Vermont,   78 
Redstone,  New  Hampshire,  67 
Reid,  H.  A.,  391 
Renfrew  marble,  21J 
Rhodonite,  193 
Rhyolite,  126 
Rice,    W.    N.,   197 
Richardson,  C.  H.,  80 
Richmond,  Virginia,  94 
Riebeckite,  57 
Ries,  H.,  342,  343 
Riverside,  Indiana,  239 
Road  building  rocks,  379 

chert,  379 

felsite,  379 

field  stone,  382 

granite,  379 

limestone,  379 

requisites  for,  379 

sandstone,  379 

shale,  381 

slate,  381 

trap,  379 

Robeson  Mountain,  Vermont,  87 
Rock,  definition  of,  1 
Rocklin,  California,  42 
Kockport,  Massachusetts,  59 
Rose  crystal  marble,  165 
Rose,  G.,  140 
Rosendale  cement,  385 
Rosendale,  New  York,  385 
Rothpletz,  A.,  138 
Roxbury,  Vermont,   307 


Ruin  marble,  204 
Russell,  I.  C.,  138 
Russian  loess,  326 
Rutile,  232 
Rutley,  F.,  236 
Ryegate,  Vermont,  77 

S 

St.  Augustine,  Florida,  158 
St.  Louis,  Missouri,  335 
Sandstone,  229 
age  of,  235 
cements,  232 

chemical  composition,  229 
color  of,  229 
definition  of,  229 
impurities  in,  229 
origin   of,  235 
texture  of,  229 
varieties  of,  231 

argillaceous,  231 

calcareous,  231 

feldspathic,  231 

ferruginous,  231 

flagstone,  232 

flexible,  232 

freestone,   232 

glauconitic,  231 

greywacke,  232 

kaolinitic,    231 

quartzite,    232 
Sandstones,  American,  235 
Alabama,  235 
Arizona,  235 
Arkansas,  235 
California,  236 
Colorado,  236 
Connecticut,  237 
Georgia,  238 
Idaho,   238 
Illinois,  238 
Indiana,  238 

Mansfield,  238 

Portland,  239 

Riverside,  239 
Iowa,  239 
Kansas,  239 
Kentucky,  239 


28 


434 


INDEX 


Maine,  239 
Maryland,   239 
Massachusetts,  240 

Roxbury  conglomerate.  241 
Michigan,    241 

Lake    Superior,    242 

rain   drop,   241 
Minnesota,   242 
Mississippi,    242 
Missouri,   243 
Montana,  243 
Nebraska,  243 
New  Jersey,  244 
New   York,   244 

Chemung,   248 

Clinton,  247 

Devonian,   247 

Hudson   River,   246 

Medina,   246 

Potsdam,  244 

Triassic,  249 

Warsaw,  248 
North  Carolina,  249 
Ohio,  249 

Berea,  249 

Buena  Vista,  250 

Euclid   bluestone,   250 
Pennsylvania,  250 

Hummelstown,  251 

Mauch  Chunk,  251 
South  Dakota,  251 
Tennessee,   251 
Texas,   253 
Utah,   253 
Virginia,   253 
Washington,  254 
West  Virginia,  254 
Wisconsin,  254 
Sandstones,  Foreign,  254 
Austria-Hungary,  254 
Belgium,   255 
British   Columbia,   255 
England,  255 
Ireland,  255 
France,  255 
Germany,  256 
India,  256 
New  Brunswick,  256     •  --' 


Nova  Scotia,  257 

Quebec,   257 

Scotland,   257 

Craigleith,  258  ;  * 
Hailes,   259 
Triassic,  259 

South  Africa,  295 

Triassic,  360 
Sandstones,  industrial  facts,  260 

analyses,  263 

compression   tests,   262 

quarrying,  260 

Githens  system,  261 
Knox  system,  261 
Lewis  system,  261 

references,   266 

table    showing    specific    grav- 
ity, etc.,  36,  265 

uses,  261 

San   Luis   Obispo,   California,   11 
Saylor,   D.   O.,   384 
Schaller,   W.   T.,   298,    335 
Scheerer,  T.,  142 
Seeley,  H.  M.,  170 
Segar,  H.  A.,  350 
Serpentine,  9,  193,  303 

characteristics  of,  304 

definition  of,  303 

origin  of,  304 
Serpentine,    American,    304 

California,    304 

Connecticut,   305 

Georgia,    305 

Maine,  305 

Maryland,  305 

Massachusetts,    306 

New  Jersey,  306 

New  York,   306 

North  Carolina,  306 

Pennsylvania,  306 

Vermont,  306 

Washington,  309 
Serpentine,  Foreign,  309 

Canada,  309 

England,  309 

Ireland,  310 

Italy,  310 

Nero  Antica  di  Prato,  311 


INDEX 


435 


Pietra  Lavezzarra,  310 
Verde  di  Genova,  310 
Verde  di  Levante,  310 
Verde  di  Pegli,  310 
Verde  di  Prato,  310 
Serpentine,  industrial  facts,  311 

chemical  analyses,  312 

compression  tests,  312 

references,    313 

uses,  313 
Shale,  267 

analyses,  268 

cements,  267 

definition  of,  267 

varieties  of,  267 
Shaler,  N.   S.,  59,  276,  382 
Shepard,  C.  U.,  305 
Siderite,,  13 

Sienna  marble,  156,  200 
Silica,  329 
Silicates,  9 

Sioux  Palls,  South  Dakota,  378 
Skeates,  E.  W.,  139 
Slate,  268 

analyses,  297 

classification  of,  270 

cleavage,  272 

color  of,  271 

composition  of,  270 

compressive  tests,  27 

definition  of,  268 

igneous  origin,  269 

importance  of  color,  272 

impurities  in,  271 

mineral  composition,  270 

minerals  of,  270 

origin   of,    269 

specific  gravity  of,  273 

structure,  272 

texture,  273 

transverse  strength,   273 
Slate,  American,  273 

Arizona,  273 

Arkansas,  273 

California,  273 

Georgia,  274 

Maine,   274 

Blanchard,  275 


Brownville,  275 

Monson,  275 
Maryland,  .276 
Massachusetts,   276 
New  Hampshire,  >277 
New  Jersey,  277 
New  York,  ,277 
Pennsylvania,    278 

Bangor,  278 

Pen  Argyl,  280 

Chapman,  280 

Slatington,  280 

Peach   Bottom,   281 
Tennessee,  281 
Utah,  281 
Vermont,   281 

Connecticut  River  belt,  281 
Memphremagog    belt,    282 
Montpelier,    283 
Northfield,    284 
Cambro-Ordovician    belt, 

285 

characteristics    of,    287 
color  of,  287 
dove,   288 

geological  relations,  285 
lower  Cambrian,  287 
mill  stock,  288 
Ordovician,  287 
purple,  288 
red,  288 
sea  green,  287 
slate  pencil,  289 
unfading  green,  288 
variegated,   288 
Benson  belt,  289 
Viiginia,  298 
Arvonia,  289 
Brp.mo,  290 
Snowden,  289 
Warrenton,  290 
West  Virginia,  290 
Slate,  Foreign,  291 
Canada,  291 
England,  291 
France,   292 
Wales,  292   - 


436 


INDEX 


Slate,,  industrial  facts,   293 

block  making,   293 

manufacture  of,  293 

measurement  of,  295 

quarrying,   293 

slate  waste,  296 

slate  waste,  Norway,  297 

trimming,   295 

uses,   295 

Smeaton,  John,  383 
Smock,   J.   C.,  245,   247 
Smyth,  C.  H.,  315 
Solenhofen,  Germany,  135 
South  Dover,  New  York,  165 
Spurr,  J.  E.,  142 
Stalagmite  marble,  210 
Stanstead,  Quebec,  81 
Steatite,  314 

characteristics  of,  314 

composition  of,  314 

definition  of,  314 

origin  of,  314 

references,  322 

uses  of,  319 
Steatite,  American,  315 

Arkansas,  315 

California,  315 

Maine,  316 

Maryland,  316 

Massachusetts,   316 

New  Hampshire,  316 

New   York,   316 

North  Carolina,  316 

Pennsylvania,  316 

South  Carolina,  316 

Texas,  316 

Vermont,  317 

Virginia,   317 
Steiger,  G.,  312,  334 
Steinman,   G.,   139 
Stockbridge-,  Massachusetts,  11 
Stokes,  H.  N.,  224,  268 
Stone  pavements,  373 

granite,  373 

history  of,  373 

limestone,  379 

sandstone,  376 


size  of  blocks,  373 

trap,  375 

Stone  structures,  404,  405 
Stonington,  Connecticut,  45 
Strafford,  Vermont,   78 
Sunapee,  N.  H.,  68 
Superdolomite,  142 
Swan,  R.,  210 
Swanton,  Vermont,  11 
Syene,  Egypt,  98,  100 
Syenite,  120,  375 


Talc,   9,  314 
Terra  cotta,  402 
Texas,  Maryland,  162 
Thatcher,   R.  W.,   312 
Thomaston,   Maine,   335 
Tight,  W.  G.,  244 
Tile  production,  1915,  357 
Topsham,  Vermont,  78 
Tourmaline   granite,   39 
Trachyte,  126 

Travernelle  fleuri  marble,  200 
Tremolite,  7,  157,  314 
Trenton  Falls,  New  York,  168 
Troy,  Vermont,    142 
Tuckahoe,  New  York,  165 
Tunbridge,  Vermont,  78 

U 

Ulm,  Bavaria,  152 
Underbill,  Isaac,  170 


Van  Hise,  C.  R.,  234,  267 
Vermont  Black  Slate   Company. 

285 

Vermont  blue  granite,  75 
Vermont  Marble   Company,  177, 

193 

Vermont  white  granite,  88 
Vershire,  Vermont,  78 
Vinalhaven,  Maine,  52 
Volcanic  tuff,   130 
Von  Morlot,  A.,  232 


INDEX 


437 


W 

Wakefield,  England,  383 
Waits  River,  Vermont,  192 
Warsaw,  New  York,  234 
Washington  County,  Maine,  54 
Washington  County,  Vermont,  84 
Washington,,   H.   S.,  119 
Washington  marble,  191 
Washington,  Vermont,  191 
Water  of  combination,  332 
Watertown    Arsenal,    Massachu- 
setts, 391 
Watrim,  N.,  296 
Watson,  J.,  97,  98,  255,  256,  292, 

313 

Watson,  T.  L.,  70 
Websterville,,  Vermont,  84 
Weinschenk,  E.,  134 


Weisner  quartzite,  235 

West      Dummerston,      Vermont, 

119 

Westerly,  Rhode  Island,  15,  71 
Williams,  J.  R.,  289 
WTilliamstown,  Vermont,  79 
Willis,  Bailey,  137 
Winchell,  N.  H.,  60,  242,  251,  276 
Windham  County,  Vermont,  90 
Windsor  County,  Vermont,  91 
Wolff,  J.  E.,  117 
Woodbury  Granite  Company,  88 
Woodbury  gray  granite,  88 
Woodbury,   Vermont,   87 
Woodstock,  Maryland,  55 


Zircon,   38,  94 


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STAMPED  BELOW 

Books  not  returned  on  time  are  subject  to  a  fine  of 
50c  per  volume  after  the  third  day  overdue,  increasing 
to  $1.00  per  volume  after  the  sixth  day.  Books  not  in 
demand  may  be  renewed  if  application  is  made  before 
expiratipn  of  loan  period. 


MAY  3    1919 

JAN  30  1922 
OC1    6 


5Nov'59CK| 


8 


R  2  4  1999 


50m-7,'16 


I  U    U.I 


370065 


CA!IFOI 


UNIVERSITY  OF  CALIFORNIA  UBRARY 


